It's not that simple. If I go to a restaurant and order at the counter tipping is typically considered to be entirely optional, in spite of the fact that the PoS system would like you to think it isn't.
Then there's the whole spectrum of space in between. What about order-at-counter but the food is brought to you when it's ready, but you then clean up after yourself? What about a buffet, where you pay at a counter, serve yourself, but someone comes and cleans up your plates?
An alternative heuristic that I've heard is that if you pay in advance than tipping is optional, while if you pay at the end it's required, but that doesn't cover Doordash.
There are clear cut cases where tipping is required, and a whole fuzzy mess in between. And that fuzzy mess gets fuzzier and messier each year as companies intentionally blur the line.
I receive service everywhere I go, from the people who clean floors and bathrooms to the people who make food to the people who stock shelves, and even do engineering drawings for me.
If you don’t like this, don’t go.