Considering all of the lack of public trust of police departments these days, I'd prefer that they don't use encryption. But, I'm sure there is more than one side to the issue.
They have the gear but few implement encryption. Most police departments are more worried about not beimg heard than of bad guys listening in. Normally only drug squads use encryption.
Also: key management is difficult.
Also: information sharing has benefits too
blasting out all internal communication is a bad way to share information (with the public)
OTOH, censoring what info you let through is, well, censoring.