Others have hit this topic, and more eloquently, but here's one counter-corporate attorney's take.
People can grow, physically and emotionally. They can die by accident, by cancer, by a street crime - and almost never at a time of their choosing. They cannot in general split a child off at will from their bodies, or invent new parents and grandchildren, or move their whole lives and assets 12 time zones away with three pieces of paper. People have not only interests but loyalties, hopes, histories that cannot be erased. People can be moved to do heroic things. People can stand up to Bull Connor's dogs while holding a sign declaring, "I AM A MAN" out of raw will and despite great fear, or face a Nazi executioner's guillotine stoically.
People can write the Analects of Confucius, "Ode to Joy", the Federalist Papers, play the guitar like B.B. King, write a sonnet, sing a dirge, bury their dead. People can resist temptation, or fall to it.
Corporations aren't people.
Corporations are large administrative virtual machines that, for convenience and ideological reasons, we pretend to be people. HAL in 2001: A Space Odyssey had a better claim at being a person than a corporation does. So does my son Noah's imaginary friends. Corporations are fake. Some people are fake, but corporations are fake - just usefully fake. Mathematics has imaginary numbers that have real-world implications; the square root of -1 is not real, in any sense, but its use has real effects in e.g. electronic engineering.
It's not that corporations are people, or even that they are things; they are less than things, less than real. While we tend to think of them as real, they are sub-real, sur-real. Apple Computer, Inc., is the imaginary sub-thing with legal rights over the some of the intellectual property on the computer on which this rant is written. The computer that "Apple" made is more real than "Apple" itself. A person working to get money from a bank holding money in the name of the square root of negative one is fully a person, unlike this computer and definitely unlike "Apple."
Our brains handle "sub-real" poorly, so we upgrade sur-realities like "square root of negative one" and "Apple Computer, Inc." to being real. We "cain't he'p it." Earlier today, I goofed off while trying to get my kids to calm down, and played a simulation game, pretending to run a public transit system in a small city. (People reading this rant who know me well will not be shocked at this display of nerditude.) That game was virtual reality, sur-real - and very entertaining. When I closed the lid on the computer, however, the logo on the machine from Apple signifies something also in virtual reality - a corporation, artificially and legally a person the same way that by convention and artifice the square root of negative one is a number. Yet my brain is quick to call my "bus" network "fake" and slower to call Apple surreal - perhaps because the illusion about Apple is more broadly held than the illusion about running virtual trains and trams and buses on a computer game.
Corporations have no "patria", no homeland, and therefore cannot be "patriotic." They have jurisdictions of formation, but literally no "mores" in the Roman or modern senses of the word. Birth and death are the most real things that we experience, replete with the full range of experience that makes us human: hope, grief, pain, joy, love, and sadly at times bitterness, resentment, jealousy, regret, shame. Corporations come into surreality by the payment of a fee, the completion of a small or large set of paperwork (usually fairly small in most US states) and a declaration (more paperwork) by a clerk.
People almost never live to see their great great grandchildren. My late grandmother was one such fortunate member of the human race; she lived long enough to see her great grandson become a father. A corporation, however, can spin off four concatenated generations of descendants with a few checks and a working copy of Microsoft Word, living to see its great-great-granddaughter - without ever attending a birthday party or having to get a dress or tuxedo for a wedding. Corporations aren't people.
A few avant garde lawyers are, more and more, advocating for animals on the grounds that they have, or should have, some level of rights. For the most part, animals are considered either property under US law or, if not property, are non-personal objects subject to statutes and regulations in the same manner as the dirt beneath them. Fish don't have rights; dolphins don't have rights; horses don't have rights. The law "protects" animals not by a theory of "rights" but by simple black-letter exercise of police power; you will get fined, billed civilly and your animals confiscated if you fail to feed your horses properly and they become emaciated. For the most part, the idea that animals have "rights" is fringe in the US. However, "MVW US Holdings, Inc." is a holding company for the intellectual property rights of Marriott hotels and resorts, incorporated in Delaware; its rights are entirely mainstream. Legally and in surreality, it is more real than Rover and Fifi, though Rover and Fifi and Spot are of course very real and MVW entirely fictional. Maybe some animals are people, maybe not, but there's no doubt that MVW isn't "people" - except in the surreality of law.
The Roman Catholic Church has, among others, two specific doctrines about reality. One is that the Church itself is the Mystical Body of Christ. Another is that Christ is Really (not sur-really or symbolically) Present in the consecrated bread and wine. Regarding the first of these doctrines, Father William Moss stated the following:
Speaking of full membership in the Church, Pius XII, in his Encyclical on the Mystical Body, said it is the society of those who have been baptized, and who profess the faith of Christ, and who are governed by their bishops under the visible head, the Pope, the Bishop of Rome.
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It is not the same as the union of a physical body, nor that of a business corporation. [Emphasis Godfrey].
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The doctrine of the Real Presence contrasts Catholic teaching from that of many Protestant churches, which in many cases regard the bread and wine or grape juice in their services as symbols or metaphors, as opposed to Real Presence. It is understandable that non-Catholics (and certainly non-Christians) would have difficulties with these doctrines or reject them utterly; they are considered dogmas taught by the teaching authority of the Church, and not demonstrable through mere unaided reason. Teaching these doctrines is part of Catholic catechesis (instruction.) Many who would reject these dogmatic teachings of the Church as "absurd" (in paraphrase of Tertullian) would gladly accept fiat declarations by a government that a corporation exists, has children, renamed its parents, split itself into two of itself right down the middle, lives forever, protects its owners with limited liability (who in turn own this person as property notwithstanding the 13th Amendment) and is actually a person. What the Church teaches about itself and its sacraments, right or wrong, is far less demanding than the mental contortions and cognitive dissonance required to make corporations appear to be real and to be persons.
Google, Inc., itself a virtual surreality that makes other surrealities, markets "Google Glass", an eyewear-mounted mobile mini-computer that can produce an augmented virtual reality for its users. How useful it would be if Google Glass could subtract from, not add to, the surreality of our environment. Corporate logos could appear as if reflected in funhouse mirrors, distorting the distortion, or with circus music that starts when focusing on a corporate logo to remind us not to be Ringling Brothers' P.T. Barnum's "sucker born every minute." Actual people - human beings acting as human beings - could be shown in illumination, as if from a medieval tome or religious iconography. When corporate ads come on television to try to make women feel like garbage about, well, everything- a major preoccupation and profit center of American corporate life - an public service announcement from Bocephus the Bull could appear, reminding the user not to believe corporate bullshit. It could track politicians like Eric Cantor who waltz from "public service" into politician recruiting and acquisition by playing the theme from "COPS" ("Bad Boys....") when their faces appear. The possibilities are staggering.
Until then, we should simply remember: Corporations aren't people, and are at most surreal. If they were real and they were people, they could attend your funeral or you could attend theirs.