How do you conclude that from that PDF? It shows almost all of the states in the US in yellow (low mask usage). While almost all of Europe (except for the UK and Scandinavia) in blue (medium mask usage)
There's even a special call-out in the PDF about the US being such an outlier:
"US states and Canada
stand out for their low levels
of mask usage compared to
many countries in Asia
and South America. "
http://www.healthdata.org/sites/default/files/files/Projects...