The number of police departments, or more specifically, the number of departments relative to population size, can vary for a number of not-so-obvious reasons.
Within the Canadian context, many communities do not have their own police departments because policing is provided by a federal (RCMP) or provincial body (OPP for Ontario or SQ for Quebec) and not by a local body. Even were those communities to supply their own policing, the sheer distance between many smaller communities would make administration of any consolidated force a nightmare.
I think as well, the fact that Americans vote for Sheriff nudges them in the direction of having a more direct correspondance between who heads up their force, the jurisdiction of their force, and who they pay their municipal taxes to. To my mind, that can’t help but encourage a higher number of administratively distinct police forces. So the number of different forces might not be as unreasonable as you imply. It might be spot on for the context they exist in.
So I think the consolidation question ought to really be asking what level or aspects of consolidation might be feasible. Communities A and B might be best served by having separate police forces with different leadership, but save a few bucks by sharing HR or some other services. Where one has communities/municipalities that border each other, they might share a common dispatch system….and I wouldn’t be surprised if they already do.