> When police use encrypted radio channels, they can't interoperate with EMS, other agencies or in disaster zones. So becomes a problem.

Depends on the system. TETRA (used in europe) can be optionally encrypted, so the police can have radios with encryption for their talk groups, but still do unencrypted communications with the medical or fire services.

Around here, they run it with encryption off though, because apparently the key management is a pain in the ass and I guess the criminals they mostly interact with aren't the types to sit around with RTL-SDR dongles capturing their voice comms.