Work at a dishwasher factory. We used to make a model with windows, they were really expensive parts, which meant that they were really expensive dishwashers for a feature that really isn't useful.
It makes sense in a microwave or oven because you can check in and make sure it's all good, or pull it out if it's done. You can't do that with a dishwasher, it just runs it's course.
Plus all you could see in the thing was splashing soap water.
Where else are the house elves supposed to live in modern homes? We don’t have servants’ quarters and the closet is packed floor-to-ceiling with vintage porn.
Also, it wouldn't really look nice - a typical stainless steel dishwasher looks clean - a microwave and oven (hopefully) look clean and tidy through the window. But a windowed dishwasher? Half full of dirty dishes for most of the day, and even when the dishes are clean they won't look neater than a plain stainless steel finish (or whatever finish you prefer)
I saw this post and was all "yeah, where the hell is the dish window!" But then reading your comment, all these points are pretty obvious and make total sense ahah.
This has me thinking, could I have a cheaper microwave with no window? I mean i guess the window has saved me a few times because of stuff getting over-nuked but I never even considered the idea of not having one.