That's why people are so resistant; the whole thing has the stench of unsubstantiated BS about it. Kinda like the TSA.
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.
Likewise, you can test your database server for all known exploits and it might come up clean, but if you open your firewall you can still be hacked if someone later on finds a new exploit. A security minded person would ask you: "Was it _really_ necessary to open that port, of could you have inconvenienced your developers a little bit and made them use a VPN instead?"
Trust me, this isn't the only rule in aviation that seems stupid, but the mindset that results in rules like this has had a positive effect on aviation safety.
So, our defense against potentially dangerous future electronics devices is a generic safety announcement at the beginning of the flight with only cursory verification that it was followed?
Likewise, airlines have a "clean cockpit" policy disallowing small talk during landings. Do they monitor the CVRs and fine pilots who break this rule? I don't think so. Will some pilots find the rule exessive and make exceptions? Maybe. But the rule still has an effect, and is in place because of previous accidents where distracted pilots have been a contributing factor.
While I think this rule about electronic devices might be too stringent, and that it will eventually change, I don't think the airlines have overblown it. Pilots will handle instrument failures gracefully in 99.99% of all cases, and then there's the fatal accident where some stupid malfunction caused the pilot to screw up (AF447, and many others before). Because they know this is a "numbers game", they try to minimize potential problems, even though they may not be able to eliminate them altogether.