Americans have a reputation for plain speaking and I’ve found that some polite expressions with modals are used rather differently here.
When I get into a cab and ask the driver ‘Could you possibly take us to Independence Hall?’ my friends say, ‘Well of course he could Vicki. Otherwise we wouldn’t be getting into the cab’. So Americans seem to be more direct than me there.
But take another example. When my American husband has cooked my dinner he might ask ‘Would you like to clean up?’ ‘No thanks’ seems a perfectly logical answer to me. If he’d said ‘Would you clean up?’, the request would have been clearer to me, so who’s being more direct here?