It’s a legacy restriction - it was just that they banned any radio transmitters, probably originally because older analogue radio transmitters could interfere w

It’s a legacy restriction - it was just that they banned any radio transmitters, probably originally because older analogue radio transmitters could interfere with the aircraft’s radios and things. I don’t think there would have ever been any legitimate concern of low-power digital devices like mobile phones causing any problems like coupling into control systems or anything... Digital radios are typically much better filtered and far lower power than analogue radios. The company I work for makes satellite antennas for ships and large road vehicles, and the only time we’ve had a problem like that was when somebody mounted a 20kW S-band weather radar three metres from our antenna. It just requires a little extra shielding in one module though.