The traffic cameras are very unpopular here. I find it hard to believe they raise revenue on balance (I have become much more reluctant to drive into D.C. since they were installed, as I suspect many other people have as well, which means less sales -- and less tax revenue -- in D.C.). And yet the D.C. government seems determined to maintain the program.
But the differece is made up by fines paid.
One second too late going through that light brings in the cash.
Some places have even shortened the time for the yellow light to bring in more money. They got caught here doing that. Nothing happened to stop them, though.