I know most call it AEST, but there are some who call it EST.

I hear timezone names can also be a slight issue at times, some Australians call the eastern time zone EST. Leap years aren’t so bad at times either though. Kind of agree with the rest of it, much of the complexity is from historical dates.

I’d argue not every job will always be 9-5, so you still get people having to explain working hours with non-UTC timezones anyway, whereas all timezone conversions are eliminated if everyone uses UTC.