For Airplane mode, if you try to use data or make a call, users are alerted immediately and a button prompts to disabled it.
There is no prompt for DND, and often users have it on mistakenly, meaning they are missing calls and texts unknowingly, resulting in a poor user experience.
As shown in this thread, we have seen that this setting is enabled on many iPhones by mistake, which means Apple should look into it. Apple should poll their retail stores and ask how many Genius' come across this same problem - I bet the numbers are high.
If you are someone that doesn't use their phone much and mostly get calls or texts then you won't really see any airplane mode warnings if you just keep on checking to see if any calls or texts came in. At least in DND you certainly get notifications. Also, in silent mode you don't get any warnings or anything else and also would similarly not hear or feel any calls or texts or anything else. But, again, no one is really calling for Apple to do anything else about silent mode or airplane mode, but somehow for DND.
People try to point out some minute differences to justify it, but the differences are just not big enough to make it that much different. It's just new, that's basically it. Just as at one point silent mode or airplane mode (or even rotation lock as someone mentioned) was for people and they learned about them and got used to them.
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I've never really thought about it before, but I'd agree with you. A communication icon with a strike through would be better. Also a periodic pop up notifying users that it's on (with a prompt to turn it off) and a pop up explaining what it does when you switch it on would be good. Apple make devices for folk that are non technically minded. They should cater for them in every respect, including this one.
Catering in very respect would mean not even giving a phone to people as they will still get messed up along the line. Apple should perhaps provide a butler/secretary to come with the phone to actually use it on your behalf so you wouldn't have to put up with its complexities.
How do people figure out how to drive cars without huge pop ups coming up to tell them they are about to go in reverse when they put their car I reverse?