How to tell if a trader is legit or not

I watch tons of trading content and I’m in a few discord groups myself so i definitely understand the importance of vetting someone before trusting any services, products or information they offer... but i always wondered how the hell people feel so justified in demanding to see other traders brokerage statements or other personal info. There is not one other industry where people feel entitled to that kind of personal information. No one calls a plumber or a locksmith for services and demand they show you their pay checks to prove they're legitimacy. No one hires a tutor and demand to see their degree and transcripts to prove they’re qualified to teach you. In any other situation, you’d analyze all the evidence that is available about said business or service, compare that evidence with other similar businesses or services, and make a decision to either trust them or not based on all the evidence or lack there of. This seems like such a normalized thing amongst traders.