I lived in France on and off for four years, never saw a window cleaner once in that time. However I have a French friend that works in Paris, and he was saying yes, in Paris, so maybe more so in the bigger cities. I know our windows opened inwards. One of the chaps answered earlier up, that they do the windows themselves and having lived there for four years, I can probably see this is the case. Where we were in rural France, self sufficiency was the way to live, grow veg, preserve, swaps etc. Use the local tradesman, apples pressed for cider, then the rest taken up to the licenced still to make calvados. Very traditional