Except that merchants can accept a tap before the final amount is known (even with EMV contactless, though I haven't seen that yet).

Anyway, I think it might actually be against typically accepted practice in the US to have a confirmation screen at all. Gas pumps don't, for instance (they just pre-auth for $100 or whatever and adjust it downward later as needed). Nor do restaurants. I also don't really remember seeing such screens all that often outside of those two categories either.