Trustless currency means exactly the opposite of what you think. It means you don't need to trust anyone, because everything can be proven and verified mathematically without any authoritative figure that you'd have to trust. That's why you can trust the system itself.
I think you have fundamentally misunderstood my point.
Let’s say I buy a widget. How can I trust that the widget will arrive? That it will do what widgets do? That it will not break? None of these are payment issues, but they might call for a refund. How can I get a refund? How can the refund system be resistant to abuse?
The answers we currently have are “the law”. If the law functions, I don’t need a trustless currency.
And I'm sorry, I won't address your other points.