So many people in this thread not realising that the UK still uses miles to measure distance on all its road signs and in cars XD.
I mean, I prefer metric anyway (mainly because I work in science and I find anything else ass-backwards) but I'm "used" to miles as a measure of distance so it didn't really bother me. I suppose it's weird that it switches to metric in other languages and there isn't an option to choose, though. We're metric everything else here, but for some reason on road signs and in cars the switch was never made (miles and Km are both shown in car speedometers with miles the dominant number). It's the only thing we still use the imperial system for.
Don't forget about stone and pints. Also, nearly the entire world uses inches to measure computer displays, automobile wheel diameters, and certain industries. Most of the world uses nautical miles and knots, and even measure flight altitude in feet. The point and pica in typography are defined by inches. US or imperial measurements will not disappear from certain aspects of life for quite some time.
Still, I believe the US implemented a process of metrification by legally defining U.S. units by their metric equivalents.
I did, however, notice that the game only let you use US units, and I thought it was silly as well.