I don't think the USians you're talking about think about the measurement systems the Southern Hemisphere and Asia use. Like at all. Because if they did they'd very quickly go "wait what measurement system do they use", although 90% of humans in general don't carry the curiosity to go and find out after having that thought. I mean, I convert to metric from imperial for other's convenience as an American ("USian" is stupid and I am tired of people conflating "America" the colloquial country with "The Americas" the continent(s) because they think they're so smart forgetting about hempel's raven)
And like. People don't bother converting metric to imperial, ever, replacing the "here's your conversion!" with some condescending smugness.