The FCC is rather prickly about electrical noise in the licensed bands, to the point companies have had to modify designs to not become impromptu transmitters on those frequencies. This is one reason power cords grow those little black cylinders called ferrite beads:

https://en.wikipedia.org/wiki/Ferrite_bead

So, in theory, a crystal set should still be a good way to pick up conservative talk radio and sports talk and you kinda get the idea it wouldn't be a popular project for kids these days given the current media landscape.