That’s an odd statement. Canada and Norway just decided to do it and did it because it was a reasonable thing to do. That’s off the top of my head, but only 7 countries are not metric, and I don’t recall hundreds of revolutions to get all the rest. I highly doubt we were the only ones. I wonder what else that book is lying to you about.
The US basically did it in 1975 as well, but at the last second they chickened out and nerfed the bill to be “optional”. They had started converting road signs in some places and such even. So close.
