In my former life, when I was a teacher (and like most teachers of course), I caught many times some high-schoolers cheating. Needless to say, those weren’t the brightest of the class, and were easy to spot even with smartphones involved.
On the other hand, one would expect students preparing Agrégation de Mathématiques, the most selective exam to become math teacher in France, to have at least some amount of morals. After all, they will become the very teachers meant to prevent their pupils frauding.
Counterexample: a few weeks ago one of the candidates has been caught cheating with a watch connected to the internet in which some pdf files had been stored…
The president of the jury banned that candidate, and issued a formal statement reminding the others that such frauds are legal offences, and that at the oral part of the exam next june the jury will be very vigilent towards fraud involving “stylos-caméra, montres Internet, téléphone, fibres spéciales, etc.“.