CD's of Radio and TV Broadcasts

I know this post is not specifically about soul releases, but it could definitely apply if there are concert recordings by soul artists, originally broadcast on TV or radio, that are "out there" someplace... Please hear me out and help me with this.

Basically, the situation is this: Recently, I have noticed a whole slew of CD's on Amazon [[some on US site, but primarily on the UK site) of artists' live shows, first broadcast over the radio and on TV shows. So far, I have not noticed many for soul artists, but there are tons out there by 60's, 70's, 80's, and 90's artists such as The Beach Boys, The Eagles, Linda Ronstadt, Chicago, The Monkees, John Fogerty, and others. These CD's come in sealed jewel cases with professional inserts and booklets. They appear "legit" in most every way, and they are sold right alongside the authentic label-released CD's. The sound quality on the discs varies. I have purchased several Beach Boys' titles, and some are excellent while others sound like the static-filled radio broadcasts that they originally were. CAN ANYONE explain to me the legality of these releases? What allows these "no-name" labels to release radio broadcast concerts? Is there some loophole that allows it??? I would sure love to know...