In many places in the US there are legal challenges to encrypting general police radio traffic specifically due to public oversite. Americans have rights of oversight over their public agencies that most Europeans do not have.

Key management in old digital voice modes was tedious. Back before we had fully descended into a fascist state, the added complexity was deemed high risk for anything besides sensitive tactical comms. Even with modern networked systems, managing the encryption layer isn't trivial, and there's a high chance that radios from different departments won't immediately be able to subscribe to another agency's repeater node until the right tech gets on site.

I don’t think there are too many left at this point at least not for critical coms. There is issues with everyone on encrypted radio as in very few can talk to one another without a bit of equipment. I recently PM’d the building of an emergency operations center and the kit we needed to make all the agencies radios talk to each other was around a million dollars.

It's not very complicated, people are cheap and try to save money in the stupidest ways. They also trust lying salespeople.

Can't tell you how many million dollar plus systems/software I've been involved with integrating at my workplace (not law enforcement related) where the main reason the damn thing was purchased turns out to be non-functional due to no one checking the sales guy's claims until the contract ink is all dry.

Historically it has been the case in the US precisely to allow public oversight. But recently more departments have been moving to encrypted radio and cellular because they know no one will take them to task.

However in my state, the vast majority is still easily accessible.