> In everyday life, the metric system offers no big benefit
That's not entirely true. An American driving across the Canadian border on an interstate can automatically go from 55 to 100. That's almost twice as much.
No it isn't. Our speedos are denominated both ways, it's cheaper, and I drive a Nissan with a V6 and paddle shifters. Not that that's much in any real sense! But neither is a Piper Archer, and those also have enough power to make 100kph feel extremely tame. It's not a high bar, is what I'm saying.