While it may be debatable how much money is raised with seat belt summonses, you will always get one if you are pulled over for something else. At least here in NY. It is definitely a revenue generator (also some points on your license).

NY is on a massive ticket blitz right now due to the financial crunch. Everything is going up. All taxes..sales tax, property taxes, income taxes, water taxes. Bus ride is now $2.00. Crossing the Verrazano Narrows Bridge will be $8.00 in two weeks. Parking tickets went up to $110.00.

It is out of control. Now the police are handing out tickets all over the place to do one thing...raise revenues for the city. 3.5 million summonses in the past nine months raising $662.7 million in fines.

http://www.nydailynews.com/front/story/83542p-76335c.html