From my knowledge US airlines are the most lax about enforcement. Any data/calls in the flight have to use local base station or wifi calling going over satelli

From my knowledge US airlines are the most lax about enforcement. Any data/calls in the flight have to use local base station or wifi calling going over satellite due to mobile signals being simply unavailable, and these days airliner crews consider it mostly a way for harm reduction during takeoff and landing. Anyway, enforcement ultimately depends on flight crew, and you really don't want to know what's the upper limit of their authority.