I suspect that cell phone useage in petrol stations came about not because of the danger of explosions, but from the problems caused by powerfull cb radios that, when the PTT button was pressed, could caused the petrol pump electronics to under read the ammount delivered (mind you we're talking about 1/2 KW) and petrol companies were afraid that phones might do the same so the myth was created. After all they were not likely to say it might interfere with the pumps otherwise everyone would be trying it on .
As for aircraft who wants to take the risk, it's along way down from 30,000ft