Bit of an unfair comparison that. While the plane is near the strongest concentration of signals, it's on the ground at the gate, when they allow phone use on board anyway. Out on the runway it'll be well away from all that and the signal strength would be a lot lower than from a phone on board.
One thing I did have on a recent flight - cabin crew came on the PA system in-flight and specifically instructed passengers to ensure their phones were switched off (it wasn't the usual turn electronic devices off call), so I wonder if an errant signal got picked up by something. Obviously not something critical as I'm still here to recount.
Anyway, as the law currently stands, Ofcom plans aside,
no radio transmitters are to be used onboard by passengers - and that includes bluetooth.
PS - Brainiac tried the mobile phone at a garage thing. They put several phones inside a petrol-soaked caravan. Nothing happened - until of course instinct took over and they detonated the caravan anyway.