You know, I do trust UL when they tell me my toaster won’t burst into flames. I think they only serve America - other countries have other ways of certifying electrical things. But they have one thing no other player has right now - credibility.
When Microsoft tells me my browser won’t spy on me, at this point I just assume they’re lying. But UL has a pretty good track record. You can hire engineers to do the hard work, but you can’t hire a 100-year track record.