Forcing them to have certainty? Yeah, that's a bad law that screws over the workers. There are people who are at home doing chores or making stuff for Etsy or doing some other contract work who would like to leave the app open and then accept a fare whenever there is one, or would like to open the app to see if anyone else would pay them for a trip they were going to make themselves anyway, regardless of whether the app can guarantee back to back fares.

Instead, laws like that cause Uber to set their hours and then they can't switch on and off whenever they please and have to work miserable graveyard shifts or split shifts if that's what they're assigned.

Meanwhile there is nothing stopping anyone from taking a job with contractually guaranteed hours if that's what they want. There are plenty of jobs like that, you don't have to mandate all jobs be like that and screw over anyone who wants something different.