I'm saying that they used to because when the iPhone was new it gave them incredible leverage. If AT&T hadn't agreed, they'd have taken it to Verizon, and still made tons of money.

They no longer get the same leverage that they had while offering an exclusivity agreement on the first iPhone. If Apple were to walk away from AT&T, both companies would lose a bunch of money. It's something of a "nuclear option," and Apple doesn't care enough about unlocked phones to waste their limited bargaining ability on it.