The initial statement seems plausible but not the reason you gave for it. Even trivial assertions involve trust. Your statement “a vow over something that they’d have no reason to trust the person on otherwise” reverses the burden of proof/trust that must be overcome. You still have to choose to trust someone even if you don’t have evidence saying that they break promises, lacking evidence proving them distrustful does not preclude having to choose to actively trust them.
The initial statement seems plausible but not the reason you gave for it. Even trivial assertions involve trust. Your statement “a vow over something that they’d have no reason to trust the person on otherwise” reverses the burden of proof/trust that must be overcome. You still have to choose to trust someone even if you don’t have evidence saying that they break promises, lacking evidence proving them distrustful does not preclude having to choose to actively trust them.