This question isn't really to debate the merits of whether more water is better but I'm very curious as to why home washers use very little water and laundromat front loaders fill up around halfway up the window.

I've heard the rationale that if HE frontloaders filled up too high then the agitation wouldn't be as good as the clothes would drop onto water rather than onto the drum itself. If that's true then how do laundromat washers get clothes clean?