Comment by mceachen

HQ audio quality (over 4G) is markedly better than land lines, and the fax protocol has had error correction since digital formats were adopted in the 60s and 70s.

https://en.m.wikipedia.org/wiki/Fax

My Palm Pilot (with a CDPD backpack) and candybar 2G Nokia could both send FAXes.

I suspect there's no demand.