The idea that other teams do this on a regular basis is unfounded.
If you want to stir the pot just to get "proof", then you'll be stirring a long time. However, MANY current and former players/coaches have gone on record (via ESPN, NFL Network, talk radio etc) saying there are varying forms of a bounty system happening all over the NFL, not just the Saints. Says it happens all the time where guys will put up a little cash for "incentives."
You, and none of us have any idea first hand... I will listen to the many respected people I have seen/heard say this does happen.
And fwiw, I am glad the NFL came down hard on the Saints. First of all I'm a big football fan growing up playing it and now just watching and believe in sportsmanship. Secondly, I witnessed the Saints bounty system take my team out of the NFC championship game a couple years ago by going hard and illegally after Brett Favre. I love big hits don't get me wrong, but there were some damn cheap shots going high/low on him.

LOL