I'm not out to 'defeat' @kencode. I am just putting out my views, but I don't know what level of proof he is looking for really. Measuring astronomical distances requires specialist equipment and knowledge.

In effect, random people on the internet are roughly as trustable as any random scientist, priest, politician, or even engineer or doctor.

I disagree with that. Trust is based on reputation which we can take from what we see them say/do and also from what others think of them. Mind you, I would say that a billion Christians can be wrong :) To become a respected scientist you need to prove yourself through exams and then by publishing papers that your peers review. I am not qualified to judge them, but I have some trust in the system.

None of us is going to read every scientific paper to understand how everything works, so you have to trust that others have read them. The system is by no means perfect, but it is all we have. Humans are imperfect too. They can lie and steal, but most are basically honest and so the crooks can get caught out.

Unlike some people here I have respect and trust in some politicians and CEOs. They are just people like us after all, not alien lizards out to conquer Earth (or whatever some people believe).

Trust should not be blind, but you get to set the limits you place on it. Yours may be different to mine. When I get on a plane I trust that it has been tested and maintained. I do not do my own inspection.