It doesn't work that way. You can't have proof of everything and claim that the lack of evidence means such activities are not taking place. Can you show me proof of what the CIA or MI6 have done in the past 6 hours, what people they are looking into, and what actions are being discussed in their meetings? Does your lack of such proof mean they are not intelligence agencies?

How do you know that UTXOs and all its history are already not being checked, compared, exchanged, and stored in some databases somewhere to be used for who knows what? There isn't going to be proof for that and open-source or closed-source doesn't matter one bit for that to be the case.