> I see doordash/grubhub/ubereats folks with big insulated bags(or backpacks in the case of bike/moto folks) pretty regularly. Not sure if they are required(or provided or sold) but they are definitely available.

They're available, but I don't think they're universally used. I read one article where the a pizzeria was offering bags for the drivers to borrow (because of bad reviews for cold delivery pizza), but a lot of them refused because they'd have to leave a deposit and didn't want to return to the store to return the bag.