From https://en.wikipedia.org/wiki/Metric_system : “The SI has been adopted as the official system of weights and measures by all nations in the world except for Myanmar, Liberia, and the United States.”
Indirectly false. Even though we don't use metric directly in most cases in the US, the US customary units have long been rebased to be defined by metric units. Inches and pounds are just centimeters and newtons walking around in a whacky outfit.
I think the point is that the US customary units are typically used in a very different way, with fractions being way more important than in metric. See the image in this [1] article that talks about drill sizes for DIY use, for instance. You guys go like "oh no the 5/16:ths hole is too small, I'll step up to 19/64ths that should do it". Over here in metric-world we go more like "oh no the 7.9 mm drill was too small, I'll step up to 8 mm".
Again, the fact that it's easy to convert the 5/16:ths to 7.9375 mm is not the point, the point is how the decimal/metric units are used in practice.