A few senators are allowed to pretend to put up a fight, just for show.. but they never actually achieve the desired results. I suspect the first thing that happens when they first take office is they're shown their NSA file and told that they have to play along if they don't want to be ruined.
I think you hit that nail on the head. They all seem compromised as soon as they get to DC.
To get along, you go along. Everybody makes money. Everybody gets fame. Don't rock the boat.
This is what the Founders sacrificed so much for.