Police depts are not stupid, they know there are scanners that decode P25 systems widely available now. In the early days those scanners did not exist or when they started being made they were expensive. Public safety thought their communications could not be monitored. Then P25 scanners became widely available and then their communications were being streamed on the internet so the need for encryption became popular. If they want to talk securely then they will. Remember even though the radio system maybe paid for by tax dollars, that does not give the public the right to be able to monitor all their activities as some people believe. Does it contribute to police misconduct, no.
No doubt encryption sucks big time, best thing you can do is make your opinion made available to people in charge of the various departments that encrypt even their dispatch TG's, hell even animal control TG's being encoded. It's my belief that TAC, UC details, and other sensitive stuff should be encrypted. The smart listener usually can figure out what is maybe going on by monitoring other traffic that is in the clear. When I worked in TV news, when the PD was being very sneaky and quiet, I would go to the fire or EMS channels and they would talk about the incident in great detail.