As I understand it, when they first became available in the home, they were so miraculous that those whose former duty it was to wash the clothes by hand would sometimes luxuriate in their newfound free time by sitting in a nice chair and just watching the clothes wash themselves.<p>Also, I reckon there was a risk of people opening the doors out of incredulous curiosity. As a child, I definitely would have tried to open the thing if it didn't have a window.
The top-rated response is a pretty solid one. People find it calming to see the washing action, even if they have no real mid-process control over it. It's all about creating the reassuring perception that your clothes are getting super clean.<p>Incidentally, this is also the primary reason why American laundry detergents are so sudsy. There is scant evidence that the formation of foamy lather has a significant effect on the removal of soil from clothing. It's mostly for show and psychological peace of mind. In fact, in many countries outside the US, laundry detergents are formulated without the abundant sudsing agents found here. We've been conditioned, over many successive generations of CPG marketing, to believe that more suds = more cleaning action. This goes way back to the days before laundry machines, when brand marketers at soap companies used suds as product differentiators. The experience of hand-washing clothes in a foamy bucket gave the impression that the soap was more effective.
I like top-loading machines because when I take the damp clothes out, it's easier to keep stuff from falling on the floor. With a front-loader, you pretty much have to keep the laundry basket right under the door. Ditto for dryers. I see no advantage to front loaders except that they can be stacked. Unfortunately, we have stacked machines where we currently live, and stuff always falls on the floor :(
So you know it's not full of water and safe to open the door.<p>(Yes, the washer will ensure this can not happen, but you the user do not necessarily know that).
It's surely to do with being able to see if there is water in the drum before opening the door. Top-loading washing machines don't have a window, and also don't have a chance of flooding your kitchen if you open them at the wrong time.
Dishwashers don't have windows, because its pointless. The constant shower of water would make it impossible to see anything. As stated by the dishwasher manufacturer quoted in the OP.
Huh. I always figured it came from commercial front-loaders, which need a window so when at the laundromat you don't accidentally open someone else's washer.
Flawed premise: All washing machines have windows.<p>Disproving premise: This washing machine has no window[0].<p>Conclusion: Not all washing machines have windows. Therefore the question is flawed.<p>Additional: There are many types of washing machines. Homogeny of design doesn't necessarily mean there's a reason for the homogeny.<p>[0] <a href="http://www.sears.com/kenmore-top-load-washing-machine-3.4-cubic-foot/p-02620022000P?sid=IDx01192011x000001&kpid=02620022000&kispla=02620022000P" rel="nofollow">http://www.sears.com/kenmore-top-load-washing-machine-3.4-cu...</a>