Earlier quoted context omitted.
But people I know who are trying this gig economy part-time can pick their own "clientele": Uber, Lyft, Postmates, Door Dash, etc... they work for whichever client they want, on their own schedule. As an "employee" of Uber, I doubt they will want you working for competitors.
See, this is key. If Uber has to class them as employees, it should also be able to deny them from working on other platforms. It should also be able to set working hours. And deny drivers the ability to refuse rides if they wish to keep their job. It could provide a daily salary and not let drivers decide or see fares. Because this is what employment typically entails.
However, if the work is part time, employees can’t be restricted from working at another part time job, unless that job is for a direct competitor of the employer, in which case the restriction is sometimes allowed. (The idea being there could be a conflict of interest or loyalty.)