There doesn't need to be an existing shortage of drivers for this to be beneficial.
Most of the money Uber is burning is to recruit drivers. If there are more drivers around, there's less of a reason to burn $100MMs to recruit drivers.
And during a recession it has been shown that people eat more fast food. So I imagine overall the business may not be so exposed.
I wouldn't really call that diversification. I mean, I take your point about fast food, but during a recession, it's probably about cheap eats, which Uber Eats is not. And time should be more plentiful, so there's less need for delivery. And UE is a tire fire of a business from these numbers, so that would hardly be a blessing for Uber.
There's some data hidden away in the middle of this news story that matches what I've heard elsewhere: Uber Eats is such a huge percentage of restaurant revenue here now, stores can't afford not to be on there anymore (and being on Menulog instead isn't cutting it):
Shade Cafe took over from previous tenants, a Greek restaurant, in September last year because 60 per cent of its business was coming through UberEats, and they couldn't justify renting such a big, expensive space. “People aren’t forced to go out," Carey said. "The amount of UberEats coffees we do is amazing, it’s crazy. It’s hard to get people out of the house.
https://www.smh.com.au/business/the-economy/the-happy-shops-...
I certainly would go carless if I lived in a city, but it hadn't crossed my mind that convenient food delivery could be the tipping point in car ownership vs not. But it makes sense -- as, for many, (commute) transport is solved.