Why not?
Or more specifically: the law doesn't require this, so why would it have to change?
The bill merely states, "hey, this flexible way you've been working, that's not independent contracting, that's employment and the employer have to abide by all these other regulations." Those regulations in no way require Uber to make workers work for specific hours, pay them hourly, or schedule their work differently. In fact, it just says, "the way you're already working, that's employment." So why do you think they'd have to change how they work?
I think most of planet earth only wants to work 1 gig or at most 2 for somewhere between 20 and 40 hours. I doubt people who want to work a tiny number of hours make up a meaningful proportion of the workforce. In other words much ado about nothing.
The benefits being discussed are health insurance.
If they have to pay a full-time employee, they can schedule the employee and force them to drive to a certain location, and do a certain number of trips, otherwise they would just fire them. They can squeeze out more efficiency from a single driver rather than hope that there's enough random drivers to fulfill all the demand.
Hiring people to just sit around and do nothing doesn't make any sense whatsoever.
Where does it say this?