Don't forget their insistence in using 12Hour clocks on transport along with AM/PM...
Yes, I fell for it once and arrived 12hours early for my flight from Boston to St Louis.
They also write dumb computer systems that output values such as 12:00am and 12:00pm. There is no such time as 12:00am or 12:00pm and when (ab)used it's then a fun game of trying to guess if 12:00am or 12:00pm is midday or midnight.
"am" is before the meridian. "pm" is after the meridian". Midday is the meridian therefore 12:00 midday cannot be recorded as being either before (12:00am) or after (12:00pm) itself. Midnight is exactly the same amount of time before the meridian as it is after the meridian therefore it makes no more sense to try to write 12:00am or 12:00pm meaning midnight either.
For example, "Tuesday 12:00am": is this "Tuesday 00:00", "Tuesday 12:00 (midday)" or even "Wednesday 00:00" (effectively "Tuesday 24:00" even though 24:00 isn't valid). Midnight Tuesday doesn't make much more sense either as it's contextual if you consider this the very start of Tuesday or a sliver of time past the very end of Tuesday.
The same logic works for +0 and -0 which I still see on occasions... although Microsoft did eventually fix this in the windows calculator.