Nor can you allow people with too much personal power to put other people in danger - which is precisely what Steve is doing. Or you can - and people die (which is what is happening in far too many places in the world right now.)

And what oversight does anyone have over the Avengers? Or over any superheroes? The people? I suspect they are the ones clamouring to get the Avengers under control.

Tony learned this the hard way, travelling from "privatising world peace' to agreeing to some form of oversight. Steve, on the other hand, appears (from the trailer, which probably does not give the whole story) to believe in his own image - that he is always right and above the law. (And, indeed, Chris Evans has articulated Cap's position as something not far from this.)