While flight attendants and intercom announcements do ask that cell phones and other electronic equipment be turned off there are no meaningful checks to see if this was actually done. That alone tells me how much an issue it is: it's pretty much an honor system. Could you imagine if that was how airport security was handled? "You don't have any knives, weapons or explosive devises do you? Excellent, please proceed."
And last I checked cell phone use on airborne aircraft was prohibited in the US by the FCC not FAA--I believe because traveling hundreds of miles per hour over cell networks was not something those systems were designed to handle.
to me it like one person said it a old wives tale ..along with now days you have inflight sat tv and internet along with phone on the planes..
it more for safety dureing a landing and takeoffs are the pilot of the aircraft are the most worryed about getting aircraft onto or off the ground and if something does happen that the worst area to have some one who is texting and will not move out of the way because they have to finish the texting that message ..for we all have meet that person when it time to do something they are on there phone texting to the person and will not move or get out of the way to have someone pass them or to move the line up in the line when it time to move ..