It is truly amazing what total nonsense people will believe in order to justify laws (or really anything else which in their view needs justifying). You can literally drive around 48 states and see that this never happens. It's not a thing. The Mythbusters even did an episode on it years ago and they decided it's not a thing; they were simply unable to get fumes to combust using static electricity, let alone cell phones.
I think you might be remembering this Mythbusters episode backwards; they determined that it wasn't cell phones causing ignition and was in fact static electricity.
