OK, more directly.

Worrying about about which measurements systems are best and making fun of them is for fools. Use the units that best fits that task at hand. And shockingly enough, it ain't always Millimeters, centimeters, kilometers or degrees Celsius. Maybe it's pounds, feet, miles, or AU's and Light years.

The US is a metric country. The federal government passed a law in the early 1970's to make it so. They just didn't pass a law forcing the change at a set time and date. They decided, for better or worse, to let the change happen organically. And change it has. Go in any grocery store and look at the food on the shelf, it's all clearly marked in US customary and grams/kilos. I know every pound of butter I buy is 454grams. My whisk(e)y/wine, (choose the spelling you prefer), comes in 750ml bottles. A bottle of soda comes in 2 liter bottles.My FDM printers use 1 kilo spools of filament. We are all looking for that same missing 10mm socket just like the rest of the world. And no one gives a rat's arse about how many feet are in a mile. Except surveyor's and civil engineers, a very small and specialized subset.

Did you know there is a error in what the meter actually is? And it's been there from the very beginning. One of the guys sent to make the original measurements decided that drinking wine in sunny Spain was better than climbing mountains and dealing with bad weather just to measure some silly distance. So he fudged it. The error has been known for quite a while and never corrected. It's still there even after the switch from using a physical item to define a meter to how far light travels in a set time, (now THERE'S a silly random looking string of numbers). Not very scientific or accurate to ignore the error now is that? I thought the metric system was better than that.

Again for the slow learners, G20/G21 the machines don't care and no one else should care anymore either.