Of course -- the majority of Americans are not employed in mid or senior level white-collar salaried jobs. Uber drivers are definitely not in this classification.
I am saying, classification as an employee does not require Uber to change anything about their expectations of their workers' work frequency, duration, or schedule. It can remain voluntary just as it is now.
There are currently voluntary hourly jobs that exist, but people here are probably less familiar with that concept as compared to salaried jobs.