But how is it better for the world if all of these Uber drivers, who clearly prefer driving for Uber to McD's, are forced to work at McD's instead?

You're assuming there's unlimited demand for employees by McD's... which, in point of fact, is absolutely not the case.

It was a single example of a low-skilled job. The generalized point is that you can go to any employer looking for low-skilled labor. There's high transferability between these sort of jobs.

My point was that there's not an unlimited supply of low-skilled jobs. The fact that if you're qualified for one, you're qualified for another isn't really relevant when they can be very hard to find in some areas.

There's been a bifurcation in employment: high-skilled and low-skilled employees are most in demand. The service industry is hurting for people. Hotels, restaurants, fast food places, etc. In fact, the NYTimes recent wrote about the hotel industry:

https://www.nytimes.com/2019/09/09/travel/hotel-jobs.html

Doesn't the worker get some say in this?

I, for one, would much rather drive for Uber than run a fryer. To the point of willing to take a significant pay cut to avoid the fast food industry.

You still have a choice where to work. Why do you think AB5 takes that away?

It takes that away with Uber stops "hiring" me because now I am too costly to have because AB5 makes me their employee.

Whether or not it's profitable for Uber or any business to hire you, is that business' decision. It's not yours to make. And there is no evidence that ridesharing companies cannot afford to pay drivers more. What if prices go up 20-30% and the level of service stays exactly the same? Then it was a silly concern with no basis in reality. I don't think evidence shows that Uber will immediately fire all drivers if they must be classified as employees.

Do you genuinely believe that this change will have no effect on the market? That the number of people driving will be the same? That everyone will just be able to continue to drive for Uber/Lyft, on the same schedule that they currently do, but make 20-30% more?

I know that the answer is "no" since you've already said "they can just go work a fast food fryer". But that's hard to reconcile with this last statement of yours.

This is an interesting read about the hotel industry. I don't think it disproves the idea though that there are people who want to low-skilled jobs who can't find them. For instance, from that article:

"The popular Mackinac Island in northern Michigan has only 500 year-round residents but approximately 3,000 jobs in the summer months. Delays on the approval for seasonal worker visas this year forced one resort to temporarily close its restaurant."

When it's their "season", they're probably hurting for staff, but when it's not, all those thousands of people are out of work and need to try to find a new job...