The am pm thing isn't everywhere, in Europe they often say "19 o'clock" so that's just an accuracy issue (honestly it's a made up problem since am pm will still be used).
That Monday/Tuesday thing is also made up since there are offices, bars and clubs with overnight opening hours and they still separate the days, made up problem.
Lastly, the entire issue one has with not knowing if the offices are open in Australia is still happening today, and we mostly solve it via Google, like we can solve this one too
I'm in Europe (United Kingdom, not mainland Europe) and I've never heard anyone say 19 o'clock, that doesn't mean it doesn't happen, I've just never heard it and I'd find it quite strange if I did.
Schedules are usually made of context: Shall we grab a drink at eight? (Nobody drinks at eight in the morning, so it must mean the evening.) – Shall we have a meeting at two? (I'm usually asleep at two in the morning, so it must mean the afternoon.) – it's rare that I experience ambiguity in times.
The am pm thing isn't everywhere, in Europe they often say "19 o'clock" so that's just an accuracy issue (honestly it's a made up problem since am pm will still be used).
That Monday/Tuesday thing is also made up since there are offices, bars and clubs with overnight opening hours and they still separate the days, made up problem.
Lastly, the entire issue one has with not knowing if the offices are open in Australia is still happening today, and we mostly solve it via Google, like we can solve this one too