You can bomb an ordnance storage facility even if there's a hospital right next to it (or, in fact, right not on top of it).
They've made sure the pagers were used by Hezbollah first and foremost, tough shit if few were given to kids to play.
And yes if Ukrainians were able to blow up all drones within say 50km of the front lines on the Russian side they'd be justified to do that, even if some were in civilians' hands.