All I would add to what you've said is that when my Bosch does include a pre-wash in a cycle, it checks how dirty the water is and only drains the pre-wash water if is dirty. If the dishes haven't caused the water to become dirty, it keeps the same water for the main wash cycle.

Also, I want to expand upon my first paragraph a little: I'm not having a dig at anyone who doesn't understand their dishwasher. I am just venting/observing that the world is filled with all kinds of different people and reminding myself that I shouldn't make assumptions about people as often as I do.

I've had this realisation many times, but it doesn't hurt to have it again. Communicating with people is lot quicker and easier when I remember that.