Cell Phones On Planes

There's been a lot of talk recently about the Samsung phones and the danger of fire.  On planes, one of the first instructions given to passengers is to turn off your Samsung phone (all phones for that matter) because of the possibility of it catching fire.  It happened the other day.  A Samsung phone that had been turned off, but held an 80% charge, caught fire and filled the cabin with smoke.  Luckily this was before take off, and the plane was evacuated and everyone was fine.  Imagine what might have happened if the phone caught fire while the plane was in flight,>p>

Here's what I don't understand.  The TSA has strict rules and regulations on what can and cannot be taken on board.  No guns, liquids over a certain amount, knives or flammable items.  Doesn't the Samsung in question qualify as a potentially flammable item?  They X-ray us, pat us down, have us take off our shoes, yet something that they know if potentially flammable can be taken aboard.   They are expecting passengers to be honest and turn off their phones, when we all know in reality this will not happen.  For some reason, the Samsung phone is allowed to be taken aboard, even though we know of its' potential hazard.  I just don't get it.