* meters
* kg
* lean celsius but don't care too much either way
* abolish seasonal time changes
* for online calls/events specify time in UTC
* YYYY-MM-DD date format
* ground floor is 0th; don't skip 4 and 13
* don't put sugar in cold tea

Simple rules for a civilized society.

Anyone who uses MM-DD-YYYY should be arrested fr fr

It probably sticks because it matches natural-language usage: "I was born on January 31, 1994"

East Asian languages are better at this: in Chinese you would say 我是1994年1月31日出生的

(So the "MM-DD-YY is a better fit for humans" thing is false, East Asia works fine with YYYY-MM-DD even in natural language)

Interestingly whether they would use 1994 or year 83?