Leslie wrote (in his comment below) about “..how we used to argue about whether the Metric or Customary was better”
That is exactly what I’m talking about! Another example: in, um, three weeks I’ll be going to France for a fortnight (score one use of the word “fortnight”), and I’ll be using Euros! Feh. J’aime le franc. J’aime also les dodgy currency changing booths around every European train station when I was Eurailing it in 1998, and it’s so sad that they’re not needed anymore.