I'm certain, given we can guarantee that 100% compliance has occurred for the last 10+ years and there are consequently no reports of phone interference with plane landings, that this is a key issue.

If that 100% compliance hadn't happened, or even, maybe 90% of people were in fact using their phones at all times on every flight they could possibly get away with it, that all the horrendous crashes would have been well reported.

Or perhaps this is a non-issue, clearly has been for so long that it is not going to become one any time soon, and I assume nobody's left their kindle or tablet off flight mode turned on in a carry-on either and forgotten...