I will get told off for my contribution but one has to say that one is constantly amazed that the leaders of the free world still use a medieval measuring system. SI units (System Internationale), also commonly referred to as metric have been around for a while now. There are of course 2 other countries that are still Imperial, Liberia & Myanmar.
I should add that as a metric Brit I still drink pints of beer, calculate all journeys in miles and measure my willy in inches.
Kitchens, which is my thing, are all about millimetres.
Unless I buy sheet material, which I always refer to as 8x4 which is actually 2440mm x 1220mm. Plasterboard for some strange reason is 2400mm x 1200mm.
If I build a stud wall it's 3x2 or 4x2 and I have no idea what the metric size is.
Somehow I get through every day relatively unscathed.