I don't like to point fingers, but lawyers can write buggy code and relase it into the wild, too.

My logic is sound. I'll reduce it to a smaller example case for simplicity. The world has exactly 3 people in it. Between the 3 of them, they can do exactly as much as 3 people can possibly do. However, left to their own devices, their efforts are not coordinated. They sometimes duplicate their efforts, and sometimes interfere with one another. You can imagine them as n-dimensional vectors pointing away from a common point.

The sum of their magnitudes defines the sphere of human influence. If they all voluntarily pointed in the same direction, they could reach a point on this sphere. If that cooperative vector is projected onto each of their natural vectors, its magnitude could be greater than their own, working independently. (It could also be less.) Those people for whom it would be greater can realize an advantage by cooperation.

So these 3 form a civilization. They decide that they will allow the others to constrain the direction of their natural effort vectors, so they are not coincident with their goal vectors. Note that prior to the agreement, they could point in any direction they pleased. They voluntarily limit their own freedoms for mutual advantage. They establish rules that still allow some leeway in choosing direction, but encourage a direction that still yields cooperative benefits. These rules run the gamut from laws governing capital crimes to the dinner table etiquette for eating escargots.

So far, so good. We have reduced human society to 3 arrows in space, and their sum vector. Take a moment to bask in the nerdliness before we continue.

Now let us imagine that the vectors of two participants are more closely aligned to each other than with the third. These two decide to form a company. The rules of the company provide additional rules that encourage different vectors from those of larger cooperatives. The two participants change their vectors accordingly, and suddenly the sum of all three effort vectors projects longer magnitudes on their goal vectors and a shorter magnitude onto the third person's goal.

The company has a smaller sphere of influence than the civilization, having radius equal to the magnitude of only two effort vectors rather than three. But the closer alignment of goals allows more efficient cooperative rules.

Being separate influences, the company rules could provide enough of a benefit that company participants could decide to break civil rules. In this instance, anyone participating in the civil agreement but not the company agreement would be able to correctly say that the company is incompatible with the civilization, and the civil rules should be amended to compensate. Perhaps it would institute a rule for corporations, to establish a mechanism for creating companies that do not undermine the civilization's rules.

Now, the two people in the company could decide to continue only under their company rules. But in that case, they should not expect that third person to continue under the civil rules. That third person may, in fact, have to conter-compensate his effort vector to achieve a longer projection of the sum-of-efforts vector on his goal vector.

By this model, any company that does not include in its ruleset all the same rules as the civilization should not expect to benefit from those rules.

The conceit that a corporation is legally equivalent to a natural person in the purview of the government is limited by the fact that the government is the only entity that sees it as a person. You have to choose to wear special glasses to see it that way. Everyone else sees it as a legal fiction, and only plays along insofar as the arrangement benefits them--that is, as long as the corporation acts in the public interest.

The facts remain that corporations are creations of the government, and the government should not be able to create anything with powers that it does not itself possess. Should people wish to cooperate using an entity with additional powers, they must do so directly, without the assistance of their intentionally-limited-in-powers government. In that case, they will be unable to realize any advantages from the massive cooperative benefits the government may access. While the private partnership can do no less than its partners, it can also do no more. Tapping into more cooperative benefits requires adhering to stricter cooperative rules.