more importantly, why do some people (me included) measure short distances in meters but longer ones in miles.
Well I might measure in metric (usually), but I’ll quite often refer to short distances in inches rather than cm – the shop might call that bit of wood 100 by 50, but it’s actually a 2×4 (and I’ll refer to it as such if actually speaking to a person). As for distances in km, as mentioned above, that makes sense for anything involving a map – hence I have my GPS set to km (though the computer on my road bike is in miles).
I always used to do height in feet despite using km for distance (when off-road), but have now made that conversion too.