There's a difference between policing and harassment. I'm not saying the second doesn't happen, as I know it does, but I've never had any issues with any of the cops I've ever dealt with, even the one who gave me my speeding fine and 3 month suspension. Police can make a difference just by having a presence, there is only a need to book someone when they do something illegal. In most cases, when people see a police car on the road, they take more care, this is all I'm saying.