> 'peace and quiet' in the classroom is mistaken for educational success.
To clarify, do you think that phones or the removal of phones leads to these outcomes? Do you think that teachers like or dislike phones? Or is the point that there are many biases both ways?
> they have rose-tinted ideas about the way things used to be
Some do. Are teachers the only ones?
> if this was a serious attempt to gauge whether smartphones are [detrimental] or beneficial, we'd have a double-blind, standardised anonymously-graded test.... Funny how no-one seems to be eager to finance such a study.
I am not sure how you would set this up in a way that does not fall victim to a dozen confounding variables. There have been comparisons of standardized tests before and after phone bans, of course, but those also fall victim to similar statistical issues.