The one I visit the most already removed the self-service fountain drink station and you need to ask them for refills.
One such time was at a Taco Bell, and I was trying to go inside because I saw that the drive-through line was massive. There was a hastily-drawn note on the door that said "go to drive-through for online pickup orders," which I thought would be pretty frustrating if you had ordered ahead! (Not that I blame any of the workers, of course.)
The solution I use is to order on the app and then they have to give you your food, either by bringing it out or by pushing it through the drive-thru window.
I think another reason for this is that it is also the easiest solution for handling the homelessness crisis. Requiring all orders go through the drive through by someone in a car is one way to avoid dealing with unhoused people looking for shelter/restrooms/water for a few hours and not spending money that they don't have.