The US uses different bolt threads than the rest of the world. Just today I had to buy an 1/4 inch long 8-32 threaded screw to fix our stroller. The 8 refers to a standard diameter in the US system, and the 32 means "32 threads per inch".
Oh, and the speedometer and the odometer. The digital ones are probably counting meters and converting though.
Anyway, the US already has the metric system for things that matter; science and most manufacturing. For things with wide reach, like distance signs, and speed limits, and quantities at the grocery store, those tend to be in customary units, because the switching cost is too high for the benefit.
Plenty of things end up as imperial elsewhere in the world, though. My lathe and milling machine dials are graduated in thous (thousandths of an inch). I've seen those on YouTube channels in other countries.