I've seen users sharing evidence a couple of times, I don't know what sites they were... I think it was Black and White and something else. They took screenshots of emails, payments, photos of money and cards, something else... I think that's the truth of life, few people want to bother themselves even a little when everything is fine. The most active users are those who are in a difficult situation or searching. Those who are fine are mostly silent, and I think that's normal. I think I would do the same in their place. Just imagine: I'm sitting in a warm apartment, drinking my coffee, I know a legitimate service and I'm sure that I'll earn enough money in the near future, I have many options for what to do... And why should I make any evidence, explain and prove something to some stranger on the darknet? There is no point in bothering myself and exposing myself to additional risk for the sake of someone like me or you. Maybe you are a bad person, a murderer, for example, and I will help you?
Sorry, I don't want to offend anyone and I myself don't know a real legitimate service, this is just speculation.