It’s tradition, that’s all. Same reason why the USA uses Imperial. Tradition. Big gigantic country, hard to change it all at once. Sheer size. Moving an elephant. Little countries have more wiggle room for change. Plus, we have the whole “State vs Federal” thing to deal with. Part of our weird political system.
It’s nearly impossible to make ANY change that affects all 50 states without some complaining. Even then, the states will protest. It’s a weird system.
If there ever was a change to metric, it would happen by one state approving it. Then the others would complain. Then that state would go back. etc.
The USA is fifty little countries that all like their independence while having momma hen watching over us. The european union is trying to be a USA but it’s having trouble. It’s not easy. Can’t believe it works here in the USA , honestly.
Our news is like that. We barely hear about any country other than our own unless we blew something up over there.
Otherwise, the rest of the world doesn’t really exist.
It’s why I don’t watch the news. I don’t like the way they influence people. Oh well. The USA has more in common with China, really. We’d never admit it, but it’s true.