You see, what you call the "standard" set of measures we call "imperial" measurements because that's literally how old it is! Some of them we were taught at school and we still use miles and weigh ourselves in stones and pounds (not just lbs so that needs some mental conversion) but elsewhere metric rules. And only my parents' generation and older use Fahrenheit.
Somewhat ironic that the U.S. stuck with imperial measures longer than England has
Though, to be fair, you did invent your own gallon. It's smaller than ours, so mpg comparisons don't work.
