The beat cop was only effective where people respected, liked and trusted the police in general and if you look back at cities like Chicago and NYC their crime rates were actually much higher in that era than they are today.
You just can’t put enough cops out there to make people behave that don’t want to and if you did you’d be living in a police state particularly with the “Us against Them” mentality that LEO’s are hammered into from day one in training.
I get along great with all our local, county, and state cops around here but even though I’m generally a very law abiding citizen the last thing I want is their noses up my pants all the time because they are paid to find violations and write tickets.