The radio spectrum is allocated by the FCC, and they certainly do enforce it. They will triangulate your ass and then legally rape you with the book if they suspect illegal transmission is happening. Licensed operators will have no sympathy for an illegal transmitter, and it has to be this way. Imagine if the radio spectrum was an unregulated free-for-all. Your neighbor could just decide he doesn't want you or anyone near him rx'ing or tx'ing, so he broadcasts jamming signals all day long. Turn on the AM or FM radio in your car, distorted gibberish on every station from so many transmitters operating all trying to overpower each other. Your cell phone won't work, people fighting for dominance on those bands, too. Police and firefighters might have to use smoke signals instead, nobody could get a word through on the radio. Radio would be practically useless if not regulated the way it is.