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.
The spellchecker! AHA. By george, I think you might have nailed it. LOL.That possibility never dawned on me & he never gave me a satisfactory explanation. (There's hardly any difference at all between the french spoken today in Geneve & Lyon so I couldn't fathom why.) Mystery solved, thanks!