Because...
> If anything, during a recession, more people will want(need?) to become gig workers.
At the same time, the demand for gig services will drop.
So, to the extent possible, things will get worse for the less-scarce workers, but they’ll also get worse for the firms, because they are already often squeezing gig workers as much (or, in some cases, more) than they can legally get away with, so they don't have a cushion to pass on the demand drop to gig workers and see no net harm.
Ridehailing increases congestion if the city's public transport system is terrible.
This is not a fault of ridehailing, it's a symptom of bad infra.
Most of those gig jobs would start disappearing
There's no job to be "lost." They aren't going to turn you away for a "job" or "fire" you because you literally aren't employed by the company. Think of it as if you are licensing Uber/Lyft software to generate leads for your own business. That is literally how they think about it and what the driver ToS says.
It is sustainable to do that if by sustainable you mean have a profitable long term business that is cash flow positive
It would likely massively hurt share prices because you’re trading growth for profitability
The best way to think of drivers is that they are customers who are licensing Uber/Lyft software for lead generation for their own business. In a recession a seller of lead generation software (Uber/Lyft) is not going to turn customers (drivers) away. It just might not be profitable for you as a customer of lead generation software to buy it if there aren’t leads, but I don’t think anyone knows what will really happen to rideshare demand if the economy tanks. I think it will go down, but it might not go down as much as one might think.
How much profit can Uber make if it cuts 'certain' cities?
Can Uber and Lyft do better? Maybe. They can’t drop wages much lower either because these people need not only to eat but to pay off vehicle leases. And the more people driving for Uber, the less each person makes due to limited demand for rides (also likely reduced in a recession), so I think there will be a limited surge of new drivers.
It could be that Uber could just drop all of its scale except where profitable, but that throws billions of sunk cost down the drain too and throws a horrible signal to the market about its prospects for the future.
Tl;dr: I believe that companies with deeply red income statements will suffer the most when a recession hits, and it follows that disposable contract workers for these companies will be the most vulnerable.
You wouldn’t “dispose” of your customers in a recession.
If anything, during a recession, more people will want(need?) to become gig workers. Uber/Lyft are generally supply constrained today. If there’s a surge of supply because people need money they won’t have to pay new driver incentives, which is one the areas that cause them to bleed cash today. Demand side will fall a little, but people will still need cheap ways to get to/from places, maybe especially if their car gets repossessed.