We’re taught both metric and US customary units in school. I prefer metric for most things, to the point I have a metric-only tape measure among other things.
However, I’ll die on the hill that Fahrenheit is superior for ambient air temperature. 0 degrees to 100 degrees neatly encompasses the range of average surface temperatures seen throughout the year in the contiguous US.
Well, Road signs Need to be changed every twenty or so years anyway. So just switch them then. Who cares if the transition takes that long?
Most people with half a brain. Besides, road signs was just one example about cost, not feasability. Other industries, like construction, have a whole lot more invested in specific units.
Again, yes it’s possible to switch, and I think it’d be worth it, but… again, go convince those industries that do everything possible to save pennies per product and tell them they have to change…