Until that happens passengers are obligated to turn them off
So we screen passengers for liquids, sharp objects and all manner of items that might cause undue harm to an aircraft or its occupants but when it comes to electronic devices, the system relies on the good graces of its passengers to dutifully shut off personal electronics. Really? That position just isn't consistent with everything else that passengers are subject to. It would be interesting I'm sure to do random surveys on transport aircraft to see the percentage of personal electronic devices left on (whether by intention or not) and happily humming away in jackets, purses and carry-ons up in the overheads with apparently no ill effects.
For years it was "please keep personal electronics off until the seatbelt sign has been shut off" but even when the seatbelt sign was shut off it was "please ensure that transmit and receive functions are disabled". Now today on many airlines the use of those same electronic devices is facilitated by onboard systems that require the transmit and receive function for use.
Yes, I am being overly simplistic and yes, I can think of dozens of reasons why it would be nice to revert back to an age when we didn't have cell phones, ipads and such. But here we are and these devices are part of our daily lives and passengers have caught up to the illogical premise that they are screened to ensure they aren't carrying too much shampoo but when it comes to personal electronics causing confusion to our doo-dads on the flight deck....well we'll just make sure to throw in the word PLEASE to ensure compliance.