I think this is probably a good thing. Even in the early 2000s, having phones in the classroom was mostly a distraction (texting, or having the ringer on and distracting others) or vehicle for cheating (also texting in those days). The only downside is in emergency situations where children should have some agency to contact family. If children could be trusted to turn their phones off at the start of class and leave them in their bags, that would be great, but I get the impression from teachers that that isn't the case.