Only because Congress is happy with things the way they are. Letting the NSA (and other agencies) carry on with these kinds of programs gives them an out no ma

Only because Congress is happy with things the way they are. Letting the NSA (and other agencies) carry on with these kinds of programs gives them an out no matter what happens. If the program gets discovered and the public is upset legislators can pretend they didn't know about it. Nancy Pelosi did this rather famously, pretending she'd never been briefed on programs she was documented to have been briefed on. On the other hand, if a big terrorist attack happens and the public is in the mood for greater leeway for security services Congress can point to programs like this one and say "See, we've been looking out for you all along by authorizing intrusive data collection." This is the way legislative politics works in the US. The goal is to put yourself into a "heads I win, tails... I win" situation, and they're very good at it. To operate with principle is to risk giving your electoral opponents ammunition when you're up for office next. If Congress actually wanted to enforce its will here you would see concrete changes. But it doesn't.