This is a special concern of the FCC, with some reason.
Radio receivers are cheap, easily concealed, and they work anywhere.
Even when broadcast radio was in its infancy, a child could easily construct a simple radio for pennies. Children can be remarkably clever, but few could do all this without arousing a parent's notice at some point. Each stage of the process offers ample opportunity for parental supervision, guidance, and control. Radio receivers are in the home, a place where people's privacy interest is entitled to extra deference. This key point highlights one way in which the Internet is much more like print media than radio.