Captain America is a champion of democracy, of which the existence and use of checks and balances is a core pillar. Why, then, is he so averse to being subject to checks and balances on his own power?
He claimed said checks are vulnerable to being politicised, but that's part and parcel of any political system: has any political institution in history ever been immune to it? In this case the check & balance of superheroes will be provided by the United Nations: Does this mean he lacks faith in the UN?
Why does Captain America prefer to reject subjecting his individual, near-unlimited powers to checks and balances just so he can remain free of politics, while apparently believing that only he has the authority to tell himself what is the right way to use his powers?