Sure, but the people that are responsible for their revenue do. There is an incentive by both parties to keep the speed limits lower than they need to be as lon

Sure, but the people that are responsible for their revenue do. There is an incentive by both parties to keep the speed limits lower than they need to be as long as that means the police department doesn't need to fund its operations through regular taxation. Police chiefs often have easier access to city councils and they pretty clearly aren't lobbying for increased speed limits.