That is so true, why only just the other day I saw a 747 explode because of such an occurance.
Ahh ignorance in its true form. You can't use mobiles on the tarmac for this very reason. Why don't you try it, stand right under the wing vent as an aircraft is being refueled on a windy 40 degree day just to see what happens. Take the battery on and off until you get a small spark. Test it out and see if you can break procedures put in place by Boeing, maybe your smarter than their design engineers, the Qantas accountants think they are.
While you are at it why not see if you can test some of their other procedures. Why not disable the cargo fire bottles, start a fire in the compartment at thirty thousand feet and see if you can land. Maybe you can do it once and then have all fire bottles removed from all aircraft to save a little more money.
Of course, if this was really an issue we wouldn't be driving tow motors and the like around aircraft, what with all the sparks and combustion that go on in an engine!
The tow motors are designed so they can't produce any ignition source. The sparks and combustion are contained in a special compartment that engineers call an engine. You may have heard of it or you could google it to find out a bit more.