"So why do you collectively keep voting for such politicians then?"
That's the whole mayo vs mustard thing. The majority of political news coverage is about a few selected talking points that really differentiates one candidate from the next. Candidates that really are different from the rest are typically labeled kooks because they aren't savvy enough to keep their mouth shut on subjects that give the media laugh tracks instead of sound bites. This ensures that regardless of which candidates remain at the end the basic authoritarian core remains intact.
Add to that the fact that the primaries are mainly attended by only the extreme members of either party and the authoritarian model is a lock. Notice there is about 50% of voters who typically stay out of primaries because they look at the field and shudder at the usually horrid selection but more importantly there is a re-run of Married with Children on that night which takes precedence.
That said, yes it's very true that we need to strip economic incentives from our law enforcement and judicial governmental departments.
Coincidentally I came across this Businessweek article by Paul Barrett on Richard Feldman and I couldn't help but think Mr. Feldman is only scratching lightly on the corroded surface of justice in the U.S.