Years ago, I knew a french-speaking guy in Geneva who regularly communicated with another french-speaking guy in Lyon by email in english.
There was no real reason for him to do it that way that I can figure, other than it was across a border and via the internet (where english has been since its inception the lingua franca).
French are very proud of their language. They probably did it that way because their spelling checkers worked in English only.
I may be wrong but I think Quebec is the only place where pilots are allowed to communicate with the tower in French.