So, Trim, if a pilot is born and raised in country X, pays their taxes, has never had a single violation, but only speaks the native language of X, they're not allowed to fly in controlled airspace?
Sorry - my post wasn't clear. I agree that a pilot born and raised in X, who only speaks Xish, should be allowed to fly in all airspace (controlled and uncontrolled) in country X.
However if he wishes to fly in controlled airspace in country Y, he should have at least ICAO level 4 in English (or Yish). If he wishes to fly in
uncontrolled airspace in country Y, he should have at least level 4 in Yish.
This has already started to happen informally around Europe - I visit uncontrolled airfields in France, Switzerland and Italy where it is clearly marked on the airfield regulations that the local language must be used - and quite rightly so. This unfortunately does not stop some visiting pilots from speaking english on the AFIS, even at the risk of locally based pilots who may not understand them.