But that's the fundamental issue, it's not actually employment. Why does everyone seem to ignore that the job of "professional driver" already exists so anyone who does want full-time employment can already do it?

Every single driver I've ever asked (in 1000s of rides taken over 7 years) has always said they prefer the freedom of being able to work when and where they want. Students, retirees, stay at home parents, and others who specifically do not want to have a FT job.