But 14:00 is what the time is and what the clock shows, not 1400. So I would say 14 o'clock if not 2 o'clock. Would you say "it's nine hundred in the morning" too? Again, it's hours not hundreds. I'm sorry but I don't understand why you're talking about years.
For context my country uses 24h time and I grew up with it.
That doesn't make sense to me. It would be a quarter to 14 if you wanted to say 14 instead of 2.
They are? I wouldn't talk about fractions of cm or km if I wanted to be precise, I would say 2,5 mm or 500 m. Half a km is approximate, for when accuracy isn't that relevant.
Talking about hundreds is American military slang/jargon isn't it? I've never heard it elsewhere and it doesn't even make sense. It's fourteen hours, not hundreds. If we're going that way, I think it'll be "twenty past fourteen" and such.