Well, it wouldn't necessarily be so hard to test a few devices on a plane. But there are thousands of models of phones, tablets, wifi cards, 3g cards, bluetoot

Well, it wouldn't necessarily be so hard to test a few devices on a plane. But there are thousands of models of phones, tablets, wifi cards, 3g cards, bluetooth accessories, LTE/WiMax cards, gps devices, etc., etc., etc. Then we get into the wide variety of planes in the air with varying amounts and types of avionics, radios, etc. And those systems are in different places in different planes. And don't forget aftermarket alterations both in software and hardware (i.e. custom firmware, different batteries) to those devices. So your test wouldn't be too hard, but the result it seems you want (i.e. a definitive answer on the safety of electronics use by passengers on aircraft) takes a hell of a lot more legwork.