So if evidence points in the direction of a plane not being effected by mobile phones, that is the hypothesis we adopt, until it has been positively falsified.
Sure, just test your hypothesis on a plane I am not on...
They also ban cell phone use in some areas of Hospitals for the same reason, and I have personally witnessed a cell phone screw up a medical device. Sitting in my Grandfather's hospital room while he is on his deathbed. My Aunt pulls her cell phone out and makes a call, not 15 seconds later a nurse came running in because some monitor on my grandfather told the nurse's station that he was dying. Aunt turned off cell phone, monitor started working again.