I can't speak to monero specifically

But:

• Why aren't they catching more criminals? They are. They just are finding alternate sources of evidence. Dick Wolf shows love to talk about how cops need to protect themselves from any poison fruit and blah blah blah. The reality is that they immediately go to the poison fruit and use that to make a plausible excuse for why they investigated something else that can confirm information they got from the illegal source. If you've ever wondered why they would think to investigate a random unrelated company that ends up being the smoking gun...
• Why didn't anyone claim the bounty? Because the CIA and the like don't want people to know they compromised it?

Back in my pure research days it was always fun to guess what the latest "big thing" was actually about. It was especially fun when you would be looking for funding opportunities and see really weird stuff that made no sense for the org sponsoring it but would have made perfect sense for a different 3LA.

It was ALSO real fun to totally never notice when certain funding opportunities dried up and then there was a big push in the news about how we need to outlaw technology those opportunities totally didn't already compromise.

Like, for the better part of a decade The Big Thing was graph analysis techniques. And the number of kids who had no idea they were basically writing algorithms to process social media (especially twitter) was downright sad. And the people who DID realize what their work was geared toward? They applied for jobs where they got paid a lot more to do exactly that without needing to pretend it is actually about data storage technologies or optimizing cell tower load.

And... let's just say that most of those algorithms ALSO apply toward cryptocurrencies and transaction logs (since they had great applications for bank transactions...) and even doing a number on tumblers and so forth.