French being an official ICAO language has zero to do with the fact that local pilots and controllers speak French at French Airports.
The ICAO legislation states that a pilot and controller must communicate in the language commonly used by the state, which is French. If one party does not know the local language, only then, English should be used.
That is the rule. the French are only complying with ICAO.
Let me add that also in the UK, ATC uses non ICAO phraseology which is annoyin and a safety risk.
Eg. Turn heading 030 DEGREES...
absolute crap!
" when established on the localiser, descend with the glidesplope" instead of Cleared ILS or Cleared Approach.
All states should get standardised, but if already this is impossible in English Speaking countries ( dont get me started on the USA), imagine how difficult this is in other countries...
ICAO must change first their own legislation, and then get serious on making sure member states conform with the rules.