From the customer end of things, when I've used Doordash I've had meals double or more in price with delivery fee+service fee+tip. Also with most places, on top of fees and tip, they artificially inflate the price of what you're buying compared to restaurant price. I'm not going to order a $25-30 meal through them because then I'm looking at the price of a brand new video game because I didn't want to go get my food.
The result is like you found. Ordering a cheap-ish $10 meal and having it go to $20 doesn't sting nearly as much, so a lot of times that's what I'd go for. And that's less than $5 tip.