That was probably because if you lived as an expat in San Paolo, you lived a very upper-class lifestyle. In France, people have a completely different attitude. They don't say hello to you when you walk past them on the street, and they find it very odd if you say hello to them. I always felt like I was getting yelled at while I was in France. In Brazil, it was much easier.
People there are so friendly.
The Brazilians love Americans, and practicing speaking English and talking to you. It's just a much more welcoming atmosphere. France is a very analytical country. People are educated to be very analytical. You find that in business presentations, there are always three points to the presentation.