The quantity is the quality.

If you can take a restaurant that used to have to have 10 dishwashers and fire 9 of them because a machine works fast - you can keep one guy around to do the tricky stains. Sure is a lot cheaper than buying 5 humanoid dishwashers.

While there are a couple stains a dishwasher has trouble with (typically things that need a presoak, like dough or parmesan cheese), I find that the average quality of a dishwasher wash is way better than doing it by hand, where it's easy to miss a spot, etc. I've also broken several glasses/dishes washing by hand, whereas my dishwasher has never broken anything.

Not even quantity. I can do dishes faster than my dishwasher if you compare end-to-end times. Now, some industrial machines are much faster, but for home use, if I had a humanoid robot that could do dishes, why would I waste space on a dish washing machine?

Dishwashers were invented because the maids kept chipping the China.