UK'er here...
I haven't worked on an aircraft since 1981, so British Airways (ex BEA & BOAC, also other companies they looked after at LHR) had exotics American (720, 707, 747, DC10) British (VC10, BAC1/11 and Trident) and Anglo/European (Concorde) so I had to have Imperial, Metric, BA, Whitworth, Triwing, Phillips, Allen, Torx, Spline, Bristol, and whatever else now lurks rotting in my shed...
I'm now a security engineer and I don't even know the names of half the security key tools I have...
We have Pints and Litres in bars, miles on the roads, and it would be nice if something standardised...
We did get rid of the LSD (L=£ - S=shilling - D=Pence... Pence...?) - 240 pennies to the pound, 120 pennies in ten-bob, 60 pennies in a crown, 30 pennies in half-a-crown, 12 in a shilling; then we had a farthing, ha'pennie, pennie, thruppence, sixpence, a bob/shilling, a half-crown, crown, a ten bob note, and there was/is the Guinea - one pound and one shilling...
Tell me people - is US currency "METRIC"...?
Signs...? Most of the Scottish Islands removed the English/Gaelic signs and replaced them with Gaelic only, so if you do not know the phoenetics you might as well poch-ma-hon, and that spelling varies...