The US also spells many words differently than other countries who use English as their primary language. For instance…most are taught to spell realize with a ‘z’…but the proper European spelling, which was the original way to spell it…is with an ‘s’…realise.
Other examples are: favor vs favour…there are many words like favor of which the American spelling omits the ‘u’.
I’m bored and rambling, hahaha. 
I remember the failed metric conversion attempt. Grams, Meters, and all that.
The thing that killed it was construction. So many houses were built on the SAE system that when you try to install metric nominal building materials, nothing fits.
We went through this when I was in the seabees in Sicily. We laid out all our building members on SAE measurements, when it came time to put up the plywood and sheetrock it was all metric sized. We spent so many extra hours and waste cutting the sizes down to fit properly.
The same thing happend in plumbing as well. All the pipes are different sizes.
It will be very hard for the US to completely convert.