The issue with switching to metric in the US is that there isn't much practical benefit that would offset the downsides. Technically, the US switched to metric

The issue with switching to metric in the US is that there isn't much practical benefit that would offset the downsides. Technically, the US switched to metric a long time ago. No one uses it in their day-to-day life. The US is economically big enough that it can easily sustain using its own standards. Since there is no practical benefit, most people don't care and aren't going to go to the effort. A vast amount of non-metric physical tooling already exists -- replacing it would be extremely expensive. For things like engineering, it doesn't matter because the units have to follow the values anyway; there are many common unit systems in engineering that are neither metric nor US imperial, and working across unit systems is something you always have to do anyway. tl;dr: low ROI and high cost to switch