They certainly do if that cashier is working the same shift at McDonalds as when he's supposed to be at Burger King. His manager will also care if his work at another employer affects his performance when he's working his shift at Burger King.
I think that's where a lot of people really overlook this. I'd be curious to see the percentages of 'full time' drivers vs gig drivers. Plenty of drivers I know just work this a couple hours a day to help cover cost of a new car or for beer money. It's not intended to support full time work. Like a small protein bar isn't meant to be a meal replacement. I wonder if Uber/Lyft should have fought the amount of time or rides that somebody can complete per day as a means to keep it really classified as a gig whereas they've set themselves up by allowing people to attempt to be full time drivers.
On call and showing up for a work request are both mandated by law in CA. That's where a lot of issues people are overlooking lay with Uber/Lyft having employees. In their current model they would have to pay drivers just for logging into the app. If the driver did one customer drive and it took 10 minutes, they would have to pay the driver minimum 2 hours.
In California though an issue with your "micros-shifts" is that California State Laws would apply things like call in pay for this and would also have to pay minimum hours for an employee showing up for a short shift. If an employee gets called in to do 30 minutes of work, the company has to pay the employee at least a certain amount of hours I think it's 2 or 4. So that micro shift of a 10 minute ride, Uber/Lyft would have to pay them 2-4 hours wages at a minimum. So the micro-shifts wouldn't work with current state laws.
https://www.employmentlawhandbook.com/wage-and-hour-laws/sta...