Forget detailed blackbox telemetry, perhaps a more pertinent question to ask is why aircraft location data is not transmitted at decent frequency (60s?) via sat comms in a manner that is not able to be disabled via the aircrafts controls. see: https://en.wikipedia.org/wiki/Analysis_of_Malaysia_Airlines_... and: https://en.wikipedia.org/wiki/Malaysia_Airlines_Flight_370#S...

Also for the other respondent about internet access, direct access is not required in many places as there are already extensive radio ground stations in use for aircraft telemetry.