Metric
USA: (Beating chest.) We’re the USA — we can do anything!
The World: Metric.
USA: Oh, not that — that’s hard.
As a US citizen, the above is embarrassing. We made a half-hearted attempt at metric in the 70s and then just gave up. I went to Australia in the late 70s and they were transitioning just fine. Prices for meats and vegetables were in both “imperial” and metric at that time, with metric getting the bigger font. They were slowly doing away with the old way of doing things.
Worked for, well, pretty much every other country in the world.
Now there’s just the US, Liberia, and Myanmar that don’t use metric. That’s less than 5% of the world that can’t figure out multiplying and dividing by 10. (And, honestly, I’m not so sure about Liberia and Myanmar any more: they may be working toward metric.) And when you figure in engineers and scientists in the US who use metric in their jobs — because metric isn’t stupid — it’s even fewer.
I think businesses could make this change where the government and the governed can’t. I imagine businesses would much rather have their packaging consistent to reduce changes across borders. Same package in Canada and the US. (Well, okay, the Canadian one has to have French on it, but maybe we could all learn another language, too.) If packaging in the US just started doing everything in metric — like, for example, liquor already does — people would figure it out. Some wouldn’t, but they’ve probably got a smart phone and can install an app.
I already try to use metric in cooking and on this site. Why? Because it’s easier and smarter. And you can generally use just one bowl to add things to by weight instead of dirtying measuring cups and spoons. And it’s more accurate! Win win!