Lol, the UK still uses MPH too. The funny thing is in the US, we learn both metric and US customary in school. When I did concrete research in college, all our work was published in metric. Our professors would also purposely mix units in problems to screw with us lol.

Our military, NASA, and some of our industries use metric. Our medicine, alcohol, and soft drinks are measured in metric. All of our scientific research is done in metric. Basically, we could fully switch to metric if we really wanted to, but tbh, there just isn't any political will to do so. Things that need to be in metric, are already in metric.