@Anonymous Whenever Americans who have homes here in my Mexican town send me measurements for their sewing projects, so I can give an estimate, its always in inches and feet, even though Mexico uses the metric system, as does the entire rest of the world aside from Liberia and Myanmar.
So I have to convert all their measurements, because I think in metric and the fabric I buy is all measured in metric.
When I've asked some to send me metric measurements, they tell me they don't understand metric. It's only the most dead simple, logical system of measurement, which is why it's used worldwide. They could learn it in 5 minutes, if they cared to.