One of the weird consequences of being a mortgage lender is I tend to know what everyone makes. I've done a number of loans for law enforcement with really good incomes, particularly once the pension is taken into account.
It's not unusual to see HPD, for example, getting six figures. Obviously they have lots of opportunities for side work providing event security, as well. I did a loan a few years ago (small sample size and obviously may be unrepresentative) for an APD captain about to retire and he had $2m in assets banked plus three houses, two of which were paid off.
In Austin they start at $60k, which is fairly commensurate with starting pay at the FBI (not sure if APD requires a degree but obviously the FBI does).
In summary, it's unlikely to be an income issue (at least locally; I know NYPD, for example, pays for shit or at least used to). I think it really comes down to leadership and culture.