@deptrai
Part of the reason:
Boeing, Airbus square off over ejectable black boxes that float | The Seattle Times
@PrivtPilotRadarTech
I like the SPOT (used it on a year-long motorcycle trip across the Americas). But many airliners already have systems much more sophisticated than the SPOT. That's not really the issue.
The real question is: should the pilot or others onboard be able to disable such equipment? What if the system is malfunctioning, short circuits / catches on fire, etc?
If the pilot can disable the equipment, for possible safety reasons -- e.g., by pulling a circuit breaker -- then it might not help with cases like MH370 anyhow.