> You maximize revenue when everyone is "speeding" all the time and all you have to do is post a patrol car there once in a while and rake in the dough.

This is the major problem with speed limits in the USA. The speed limits are set to ensure easy revenue collection, not for safety. Nearly every single person on a given road is speeding, so they just send out officers and collect fines, regardless of whether or not the people fined are actually driving dangerously.