I know when i cut out excess refined sugar and barely ate any candy, fruit suddenly tasted better and sweeter. Now things like cola or candy are too sweet for me to enjoy. I’ll maybe have a handful of candy when previously i could eat a whole meals worth.
Most people have a hard enough time getting their car close enough to the window to get the food or to handle the card reader. I doubt many people would enjoy the toucn screen ordering as the would struggle tk get close enough and may have to lean way out of their window to order. The touch screen would also have to work reliably while wet or freezing cold.
Then you’ve got the issue of someone has to clean it and even with regular cleaning it has a huge potential to spread germs. Ultimately with all the disadvantages i think it would be too slow, too inconvenient, and add extra real estate to the drive thru.