I can't resist throwing my hat into this ring!
My general experiences of interaction with other people at DLP has been negative. I think I am a likable chap and pretty easy going but have more than a few times got into altercations with other guests because they have been rude and disrespectful - two things I will not stand for. I have had no real issues with the CMs other than a few being indifferent to customer service as opposed to downright rude.
As another worldwide traveller (lots of us, isn't there?!) I can confirm that in my experience customer service has been better in both US Disney Parks than in DLP. However I can also confirm that general customer service everywhere else in these countries was better in the US.
At the risk of coming across as xenophobic, when I visit DLP I simply remember that it is in France and adjust my customer service expectations accordingly.
Anyway, sympathies to the opening poster (who seems to have left the discussion). Whether they should have taken a wheelchair with them is a moot point. This guest felt that they had recieved poor customer service and has every right to complain about it. They just don't seem to have gone to France with their eyes open - although they were probably wide open by the time they departed.
I believe that the behaviour of some of the guests at DLP is unacceptable and don't wonder that some CMs become a little jaded when encountering such behaviour on a regular basis. But that perhaps is a topic for a whole new thread....