Saying someone should show tax returns to run for a high office seems quite a different thing that saying that we should doubt someone's wealth unless they show tax returns.
Are we saying that running for political office is reason to require someone tax returns to prove a claim level of wealth?
I'd generalise a bit and say that anyone running for political office should show evidence for claims of fact, purely because supporting claims with evidence is a critical part of running a rational and informed society.
If you don't want to provide proof, don't make claims.
Are we saying that running for political office is reason to require someone tax returns to prove a claim level of wealth?