Even the frequency coordinators are not a good source of information sometimes. A recent example would be the coordinator in Florida. They didn't make the list of repeaters public and refused to process requests for new repeaters without the new applicant having inside information into their list of approved repeaters.
I believe that group has been taken over by new leadership and is on a better track now.
I think the difficulty with ham radio scanning is the distributed nature of how it is put together. There is no requirement for there to be a centralized list of repeaters, in fact, the requirement is only that your repeater can't interfere with anyone else. There are certainly repeaters that are not documented anywhere that have been running for decades, and also documented repeaters that have shut down, where the owner either died or isn't the one that documented them so the current owner does not know how to remove that documentation.
I like the fact that ham radio is decentralized in this way, but it does make scanning it more complex.
I know by using discovery on my 436 that there are at least ~300-ish ham repeaters that can be picked up from the discone antenna on my roof near San Jose (probably due to the tech community in Silicon Valley). The Northern California coordination committees list less then half of the ones I've logged.
RepeaterBook lists 80% of what I've logged correctly, 10% are listed but are somewhat incorrect, and also lists an additional ~120 repeaters that I've never logged being keyed up. The additional repeaters sometimes share frequency pairs and callsigns but are simply listed in a different location.
Since I don't know which of the duplicate entries are correct, I can't submit a change request to any database in good conscious. I also can't submit a change request for the ones I've never logged as running, since they could start transmitting the moment I turn off the scanner.
The list I've submitted earlier in this thread is my "best effort" of just combining a bunch of online databases and doing some WAG programmatic de-duping. I don't particularly care if I have "dead" entries, since the scanner simply won't stop on those entries. My list is "good enough" that I'm able to listen to what is going on nearby as I travel around the country for work, but it is by no means an authoritative list. It is slightly better then simply programming in the approved repeater pairs for each region, since most of the time my list will display the callsign correctly and give you a good idea about where the repeater could be located.
Mostly, I like using my list because it lets me get rid of a bunch of digital noise that I would otherwise hear by programmatically removing repeaters that the online databases say are digital modes that the scanner does not know how to decode. Listening to Yeasu's Fusion digital mode or slow scan TV as FM is painful to the ears.
