Interesting that you say the 'o' to explicitly indicate the 24h format. In France we just say "let's meet tomorrow at 8 hours" for example, to which the person

Interesting that you say the 'o' to explicitly indicate the 24h format. In France we just say "let's meet tomorrow at 8 hours" for example, to which the person has to ask something like "Wait, do you mean at 8 hours or 20 hours?" It's usually obvious from the context, but not always.