Agree absolutley with you Vince, and that's a bit worrying because I am by nature argumentative. I thought you would have a deeper view than my than my one as you have been doing it longer.
Yes they(the windows) are and do stay cleaner. And you are in a better position to judge if you live in a large house.
When I was baiting apwc I suggested a national window cleaners week so that we could be appreciated more, I also said that the 'feel good factor' of having one's windows cleaned had been largely ignored. This is similar to the point you are making, that in some ways for a woman a good window clean is akin to a visit to the hairdressers.
Modern Marketing these days stresses experience. Star bucks don't sell coffee they sell the experience of sitting in their shop, Harley Davidson don't sell motorbikes they sell a dream.......The examples go on and they are not mine but what it boils down to is that a fancy hair dresser can charge more, and a designer label is sought after at a premium price.
Translate this to top end window cleaning can mean money. Bear in mind that the Japs make bikes cheaper and faster but they don't command the HD price or kudos.(for 40/50yr old men to keep in their garage undirven but with the aforsaid feel good factor)
About freqeuncy of own cleans, the next time your wife is out say you did them.