It,s not just an american problem to often i hear people reading back all that they hear and not just the things that require a read back and this is not just a pilot problem some ATC units are as bad , but the real problem is that so much importance is placed on "the radio" that some students treat a radio failure as a grade A full blown emergency and not as the minor irritation that it should be.
You should hear the rumpus when an aircraft joins the CCT non radio and as for light signals how meny of you can remember them ?.
Once you can convince people that the radio is nice to have but not nessasery then they feel a lot less inclined to speek forever.