Simple, No one but the USA (and Malaysia or somewhere) uses them. So, the USA uses them, and they're not in general use.

Pretty odd logic you have there.

Why not just go the whole hog and say Metric is obsolete. After all, the chances of aliens in other universes using it is small, so we're likely the only ones using Metric.

edit: The UK is also pretty non-metric.

I guess that is how most Americans see the world, the rest of us are aliens.