Actually there are a lot of (metaforical) burgers to flip. With the increase of free time and disposable income tourism has boomed since the 60s and whole nations are dependent on service sectors.
There have not been so many restaurants, bars etc in history as from the second half of the 20th century onwards.
If everything is automated but nobody there with an income to buy good or services those automated facilities will be pointless and ultimately self defeating unless implemented in a society that accommodates this development. Think Mincome or such things.