Does the the HP-1 download frequencies/TGs with Deprecated Tags? I always figured that scanner softwares ignore those along with telemetry frequencies or talkgroups marked as encrypted, etc.
When I get submissions like "all traffic is now on X, nothing heard the past week on Y" then X gets marked as Deprecated. The problem is knowing 'when is the old freq/system obsolete?' Agencies will sometimes fall back to their old systems when problems arise so they aren't removed altogether (right away) unless someone submits personal knowledge that the equipment has been removed or submits that the frequency hasn't been used for an extended length of time. Also, when submissions come in, I don't always know if this frequency change is permanent or temporary.
Often times the old info never gets removed because it's a lot easier to confirm that something is now in use vs something is never used anymore (especially for sparingly used frequencies that can go unused for months only to become active during an emergency). Without personal knowledge of the area, we rely on submissions.
DB admins follow scanner groups, the forums, their own observations, and submissions, but things do get missed. And if you see something wrong, send a submission and it will get sorted out.