It gets a lot more complicated than 35k robots>$15 an hour.

When building a new restaurant (Which rarely happens), sure. It would probably be more cost efficient to have automatic systems in place for certain tasks. Right now most restaurants have an automatic drink station at the window. Something similar is possible for other items like meat and buns.

At a new restaurant it would probably make sense to have these put into the restaurant and replace maybe 1 worker during peak hours. Other times in the day prep and cleaning need to be done (especially in the grill) that can't really be automated. Not to mention assembly. So as far as the kitchen area is concerned, you can replace 1 person during the lunch shift. And again, this is only viable for new restaurants. Stores that have already been built don't have the room for these things to be implemented and it would mean selling off old equipment.

What else is there to automate? Sure you can put kiosks in the restaurants, but it's going to take a long time for people to get the hang of those and the stores that they've been testing them at aren't having a great time. Again, stores that are already built aren't necessarily going to have the room for these and it would cost a fortune to renovate to accommodate them. And still, best case scenario you're removing 1-2 order takers during peak hours.

Beyond that, you still need people to put the items on the tray and bags, getting things like cups, restock, clean, deal with customers, and hand the food out.

So spending tens of thousands on renovations, automation, and maintenance to replace 2-3 workers during peak hours isn't going to be appealing to any business owner.