That said, there is certainly a good reason for minimum-length shifts and on-call payments in other industries, so I'm willing to acknowledge that striking the right balance that protects workers across the board might be difficult.
Your freelance tutoring is not employer/employee work. You're a freelancer. You set your own hours and rates.
Lawyers do not work for multiple law firms, choosing which firm to work for as they see fit. Whereas drivers very often work for both Lyft and Uber (and Postmates or Grubhub, etc) at the same time.
But to go back to the tutoring example: if I was working for a tutoring company, agreed to take clients between lets say 1-5 PM, and the rate was set by the company, would that be similar enough?
What the word "employee" means within the context of California labor laws is probably quite different from what we understand it to mean in everyday conversation. What one can imagine might work in an abstract sense may not be even remotely possible within California's legal framework. What is known to already happen and work well in other states isn't necessarily possible in California, either. (At least not without getting the legislature involved.)
We often think of "on the clock" employment in terms of shift work, where the worker has a scheduled, fixed-length shift with a single employer, and whether they're actively working during that time or waiting around for the employer to tell them what to do next, they're paid for the hours on the clock.
But it is possible for ridesharing companies to employ workers in "micro-shifts" that last the duration of a single ride.
So, Driver X has two part-time jobs: as a part-time employee of Lyft and a part-time employee of Uber. Driver X is ready to work, so checks the apps, and sees there's a Lyft assignment available. Driver X accepts the ride, and for the duration of that ride, he is working exclusively for Lyft, and Lyft pays him for the time worked. Once that ride ends, his micro-shift with Lyft ends, and he's now available to work for either of his part-time jobs again.
The idea of micro-shifts may seem, at first blush, more like a contractor relationship than an employee relationship. And in the past, gigs that used this model were more likely to involve a contractor relationship -- but they also gave the contractor much more freedom in terms of HOW they accomplished the work.
In contrast, if you look at Uber and Lyft, ignoring the micro-shift aspect, there is very little difference between how those jobs work and how other service-oriented part-time jobs work, in terms of the power the employer has to dictate HOW the work gets done.