* 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.

some good suggestions. What are your thoughts on mph and km per hour. I don't tend to mind that one too much.

Hello from the Basque Country /drip-haus @artwithhumans
Not Financial Advice 

km/h is better, better to dump miles entirely imo

Though for fuel economy I prefer (distance unit) / (fuel quantity) rather than the reverse; that's the one good thing that MPG has over the Canadian standard (L per 100km)

I'd like to know if mph and temp/height measurements in the USA now have more of a nostalgic effect. I studied nursing (RN) in Australia and one of the interesting and sad case studies we read was about an error made from the confusion of measurements between the two countries.