the license on my open source code is a contract, and they ignored that

if they can get away with it (say by claiming it's "fair use"), they'll ignore corporate ones too

If I were to go out on a limb, those companies spend more on tech companies than you and they have larger legal teams than you. That is a carrot and a stick for AI companies to follow the contract.

no, it's not an incentive to follow the contract

it's an incentive to pretend as if you're following the contract, which is not the same thing