> they have to make sure This is the problem, though. They don't make sure! They politely ask you to turn your phone off. 50% of people comply, 50% don't. If

> they have to make sure This is the problem, though. They don't make sure! They politely ask you to turn your phone off. 50% of people comply, 50% don't. If they actually had to stop the signals, they would ban all cellphones in the cabin. They could collect them, put them in a lead case with the luggage and move on. But since they don't "make sure" of anything, I disagree with your explanation.