Maybe one day someone makes a dishwasher that can do continuous washing efficiently, dynamically adjusting for the number, type and locations of the dirty kitchenware. Until then, it feels super wasteful.
It does, but our feelings are likely miscalibrated here. Dishwashers are insanely efficient.
> You use more water, more salt/dishwasher cleaning chemicals, and more electricity on empty runs.
Unlikely. You're still running the same programme at the same frequency (you were always going to run the dishwasher when you ran out of bowls, the only difference is you have some extra clean spoons in the dishwasher when you do).
> The clean dishes and utensils getting extra wash degrade faster
Technically true, but when was the last time you had to replace a spoon because it had worn out? And how much did it cost when you did?
> the machine itself wears off faster too.
Maybe. Not convinced. You're not putting any extra dirt in it, and the sprayers etc. are likely designed to handle a full load (e.g. the shelves will always be balanced, because you'll always have a full set of dishes when you run the dishwasher).
So you end up washing those 15 spoons again. Big deal. Or you notice that you consistently have leftover spoons in the clean dishwasher and put some into storage, or get rid of them.
On average you use more or less the same dishes each day, so you reach equilibrium pretty quickly. You wash a bit of stuff that was already clean. It's no big.