If I own a plastic company I can easily write an agreement where, for example, Widget Co. agrees to buy only my plastic for some price. Now imagine a state legi

If I own a plastic company I can easily write an agreement where, for example, Widget Co. agrees to buy only my plastic for some price. Now imagine a state legislature came in and said that Widget Co. can't write that, that Widget Co. always has to be open to buying plastic from other companies and that when we spend a bunch of time negotiating price and writing a contract, Widget Co. can just run that to a competitor and write a new for one cent less. That's obviously infringing on my ability to write contracts. But then we do that exact thing when the product is labor and not plastic. Your freedom of association is on the macro level, as in you can go from firm to firm to firm and if that firm requires you to join the union you just keep moving, same as if that firm pays a low wage or has no health insurance or anything else.