Right there in the name: Police Officers.
First and foremost, their job is to police society on behalf of whoever is in charge here. They don’t answer to just anyone, they answer to the people that sign their paychecks, and while on some level that might be you or I when we pay our taxes, it is actually the local Chief of Police, who in turn is paid by the Mayor or whatever the local executive body is, who in turn has his own ambitions which are balanced against the interests of his constituents. But since he is only human, his ambitions generally win out whenever and however possible.
In every city in every century, you’ve had an upper class, a working class and a dissatisfied class. Some members of the upper class might be less than satisfied because they’re not the mofo in charge today. Some members of the working class might be dissatisfied because they just got stiffed by whoever writes their checks and they went home to find another guy in bed with their wife. In either case, the police might be a nice cudgel to have, but it isn’t always the best one for the job at hand.
Members of the dissatisfied class are professionally dissatisfied for lack of any other profession. The police are around to deal with them and any dodgy looking outsiders that wander into town. If a rich aristocrat has a well paid job for them or their good buddy from the bakery down the road needs help teaching an adulterous woman and her last night’s partner a lesson, the police are absolutely there to help “you”. Otherwise their business is that of policing society and enforcing some codes of conduct. They might be common things that people do, don’t do and their common expectations as to what happens when they do or don’t do those things; or codified on some stone tablets for all of civilization to see; or simply a canonical list of vices and virtues. Either way, it’s a good stick to beat the dissatisfied with and someone needs to do it.
Social work isn’t police work, police work is preventing the complete breakdown of society by the judicious application of the State’s monopoly on violence over a sufficiently large area.