That's not the case, although certain people chose to interpret it that way. The BA wording is pretty clear that all electronic devices should be turned off for take off and landing. That's unambiguous. It then goes onto say something like devices with a flight safe mode can be used during the flight, but flight safe must be enabled before departure. And somehow that translates in people's heads into an ok to leave things on, so long as flight safe is enabled because it's more convenient to them.

(when discussed on a previous thread in the BA forum, the exact wording from the video was produced which showed that those who said it didn't say to turn things off were wrong and were hearing selectively what they wanted to hear - apparently not the statement that 'all electronice devices should be turned off for take-off and landing').

The BA announcement on switching off needs to be revised then, as it is ambiguous and those of us who have heard it many times still may be interpreting it wrongly. Occasional flyers will have no chance then. It should say that you should switch to flight safe AND THEN switch off completely, if that's what is intended. Still, no headphones allowed, and I always switch my laptop wifi and bluetooth off prior to departure but I always then just put it into hibernate.

I wasn't saying that statutorily they were trying to achieve two aims at once, just that there is a good reason for complying with the "completely stowed" instruction. The secondary effect is actually just a mental burp on the part of the airlines and the FAs, several actual rules are somehow getting combined into a jumble that's opaque to you, but still can be traced to actual FAA rules.

The underlying FAA regulation for the US is part of 14 CFR Part 91. In that maze of rules is section 21(a) which says:

and then down in (b)5 it says
finally section (c) covers the airlines:
Nowhere does it say "completely off", nor does the FAA actually take any responsibility for deciding this list of "Approved Electronic Devices". Instead the airlines collectively use the RTCA to do testing on equipment and report findings. Things tested by the RTCA become the list of approved devices. The whole song and dance is better detailed in an advisory circular from the FAA detailing the history since 1961 of Portable Electronic Devices (PEDs): link.

Farther down in the FARs you'll find 91.523 which talks about carry-on items, but does not specify when these items need to be stowed, only that they be stowed in a way that prevents them from moving forward in the event of a crash or crash-like sudden stop. The airlines are likely mentally combining this rule with 91.535 which is quite specific that the aircraft cannot be taxied, take-off or land with food items at the passenger's seats, with service carts not stowed, with tray tables or seat-backs in the "wrong" position, and movie screens in the aisle-way.

But underlying all of this is that the airlines and the pilots fall under the 11'th Commandment - "thou shalt not f*ck up". Anything which might get the airline in hot water will be viewed by the airline lawyers as a no-no, and the fact that prohibitions on items might be non-sensical, or that things are not consistently applied on every flight, is a dont-care so long as liability is somewhat constrained. Airlines have cart-blanche to tell you what to do with your laptop, headphones, and kindle, because if something does happen, there's a trigger happy trial lawyer somewhere ready to sue because your laptop was on.

My advice, consider your friendly (or not so friendly) FA to be the equivalent of a municipal motor cop, if you are in his/her sights, all the kvetching in the world about laws and constitutionality wont keep you off the hood of the car face-down in hand-cuffs. Be polite, follow the instructions, and if you really feel your civil rights have been trampled, file a complaint. It seems like at least on UA (for now) you'll get an eCert for your inconvenience. Even better, do a little prep in advance and be prepared for arbitrary instructions like forcing you to pull the battery to prove your device is 'off'. Thats the way it is, just like your parents used to tell you, "because and I said so" (and the US Government made it that way).

Conversely, if you are polite and compliant, you will have a more pleasant flight. FAs have ways to make things easier for passengers they like.

I always try to be the easiest passenger on the airplane, and as a result, I get excellent friendly service.