I feel this is something like identity politics, and something that really does not need regulation except to allow those to identify however they wish, with no determent to others.
Corporations are made up of people, yes, but giving them personhood is a pretty dangerous idea. Should they get to vote? Obviously, the answer has to be "no" or else people will register companies to rig elections.
If they can't vote, are they really people?
If they aren't, then what exactly are felons and foreigners?
This logic is hugely flawed. Since we work off of a one-person-gets-one-ballot system, grouping people together (as in a corporation) and giving them a vote wouldn't make any sense. By contrast, you can't "use up" your speech rights: Each person is allowed an unlimited amount of legal speech, and I don't think there's a compelling philosophical argument that a group of people speaking together isn't protected. There may be _pragmatic_ arguments, but that's another ballgame altogether, since the entire point of the Constitution is that it's _not_ subject to the pragmatism/whims of the time.
I'm not saying that "corporations should be legally modeled as people" is an ironclad truth, but none of your objections make sense.
In reality, the argument is that you can't restrict a corporation's speech because using a corporation to speak is merely a form or method people use to speak.
You could speak via billboards, grass roots organizations, a radio show, lettets, or even a company you own.
The government can't curtail your speech no matter the method.
The people who comprise a group have no extra vote to give: if two friends and I form a group, a new vote allocated to the three of us doesn't magically materialize. By contrast, since there is no quota for speech per person, two friends and I can form a group (eg, an advocacy group) and tomorrow go down to Union Square (or buy airtime, or hand out pamphlets, or stand on a street corner) and engage in whatever legal speech we like, collectively. The claim is that if that group of people happens to be given the structure "corporation", that doesn't automatically allow for infringing on the rights of the people within the corporation to engage in legal speech.
Again, I'm making no statement as to whether I think this approach is wise or good for society or not, but it's astonishing how common it is to see people who completely don't know what they're talking about on this issue and yet are somehow super passionate about it.
Why shouldn't a corporation, effectively a person, use the vast wealth at it's disposal to influence elections and steer government policy in the direction it wants?
Hmmm, perhaps we should rethink this whole corporations as persons thing.