Do they also make them harder and stronger?

But seriously the question here is if they can robots to do the job for lass than humans.

If the robots are cheap enough to buy and own, you have sovled the problem of "Nobody wants to work anymore (for what we are paying)".

If the robots are more expensive to buy and maintain than a minimum wage human, you will have to pay people more.

Considering how often machines break down in your average fast food franchise restaurant (especially thinks like ice cream machines) and that some other industrial robots can be quite expensive, It might take some time before they become a common sight.

Work it harder, make it better
Do it faster, makes us stronger
More than ever, hour after hour
Work is never over