AT&T had profits of (approximately) $7 billion on revenue of $31 B in 2012. So these reimbursements amount to something like 0.015% of revenue, or 0.1% of profits. For a firm that size, there are much greater incentives to lobby for favorable rules on employee health benefits, spectrum allocation, or consumer relations. I mean, over that time period the CEO of AT&T earned about $100 m, so in theory he could afford to take the hit for all that fee revenue personally and still make more money in a year than most people see in a lifetime.

I'm not expressing support for the NSA's activity here, I think this sort of data vacuuming is quite dangerous. But viewed in the context of actual corporate revenues, I don't think it's realistic to say the government is bribing big business here, because the amount they're paying is trivial, and thus largely reflective of the change in the actual operating cost of the corporate data centers.