It makes somewhat more sense to say that 3 countries have trouble exporting to the other 192 than the other way around.

No, rest of world is much more likely to use metric than imperial units.

E.g. Japan use metric: https://www.kubota-chemix.co.jp/dcms_media/other/20161226_en...

No, because the other regions of the world also use metric. America is an outlier.