My friend ordered car parts from Japan thinking they were in imperial but they were really in metric.
In my job in electrical design, the mm/mil question is a continual PITA, with half of things being measured in one and half in the other.
For example your typical two-pin passives can be measured in EIA/JEDEC standards (imperial) or in metric. An EIA 01005 is about 0.01" by 0.005", but about 0.4mm by 0.2mm. An EIA 0402 is about 0.04" by 0.02", but about 1.0mm by 0.5mm. Confused yet? I have trouble keeping it straight, and I yews them every day.
If the world were self-contained like it was centuries ago when the imperial system was invented, the only people who would care would be merchants, and they would get used to it. But the world is getting smaller; I can order stuff from any country in the world online. It make sense to move to one standard of measurement. Global currency is an entirely different question due to its political implications.
I've pretty much decided I'm going to boycott imperial to the greatest extent possible. Maybe I'll carry a conversion chart around so people can work out what I'm talking about.


