Bartender and cook are already automated and waiting for wage demands to be implemented:
Robot hamburger factory makes 360 Gourmet Burgers every hour...
http://www.freerepublic.com/focus/f-bloggers/3100817/posts
From Bellhops to Burger Flippers, Robots Look to Steal Even More Jobs
http://www.freerepublic.com/focus/f-chat/3192770/posts
I suspect it won’t be long until the typical fast food site has 2 employees per shift, mostly for logistics and sanitation.
There’s a HUGE difference between flipping burgers and creating a meal from raw unprocessed ingredients.
One is a purely mechanical act, the other is a creative art.
A device that can create something original and delicious from a standard grocery bag has yet to be invented.
As for bartender, would you go to a tavern or sit down formal restaurant where there is no staff other than table clearers? I actually LIKE the staff at my local, and they earn a decent living from their tips. The same goes for when I go out for a meal.