There's pretty much no regulation of NIL. The NCAA doesn't want to touch it for fear of being slapped down in court and having to pay massive damages, so they've basically punted on it.

As a result it's a patchwork between different states, each of which have their own rules. And some states don't actually have ANY rules, meaning that it's up to the schools to determine their own policy. As an example, BYU's Built Bar deal paying ALL walk-ons and scholarship players wouldn't be legal under the laws in several other states. Some it would, some it wouldn't.

So if BYU can say "Sign with us and we...sorry, I mean Built Bar... will pay you $1k/semester as soon as you step on campus"

Why can't Nebraska say "Sign with us and we...sorry, I mean corporate sponsor X... will pay you $10k/month as soon as you step on campus"?

It's the same concept, just differing amounts of money.

It's like the old joke about the man who asks a girl if she will sleep with him for ten million dollars. She hems and haws, but knowing she'd be set for life, she ultimately says that yes, she would. He then offers her five dollars for the same and she immediately slaps him, saying, 'What kind of woman do you think I am?'
His response? 'We've already established what kind of a woman you are. Now we're just haggling price.'