It's two things:
Their bargaining power relative to yours; and
Their bet that the consumer wants instant gratification and will sign whatever to get it.
Good points. And I would say the latter more than anything.
Especially when you figure in a deal like snags and his new sweet keen ride with heated seats and voice command texting that doesn't actually let him text GH back while driving into A town. He would have signed his nuts away for that truck if he'd actually had them.