Bang on the money, sitigeltfel. Banning mobile telephones in NHS hospitals is entirely down to protecting the commercial interest of the third party provider (that still ran up a whacking great loss despite the high call charges). I've had this said to me by several hospital execs. Last year on the other hand I spent three days in a Nuffield hotel - sorry, hospital - and could use my mobile telephone as much as I liked.
I have had two conversations with fuel station owners about the ban of using mobile telephones on forecourts; I don't do this simply because it is a serious distraction whilst dispensing volatile liquid and it seems this is exactly what they are interested in, not an ignition source from EMF.
Several conversations with electronics engineers in the aviation industry gave the view that banning mobile telephones was also more down to distraction in a potentially dangerous environment, and consideration for those around. The first of these fits quite well with permitted usage on some carriers today at 3000+ feet agl.
Out of interest; I accidentally left my smartphone switched on all the way from LHR to SIN last year and (to my surprise given FL380 at the time) had "welcome to Vodafone Poland" to prove it when I arrived at my destination!