If the radio stations don't own the rights of their Miles Davis recordings and don't have the right to license them, then why didn't the actual owners for instance stop the Dragon set, which was released way before the old 50-year EU copyright limit? As Kevin posted above they did so with other releases. Furthermore, as was discussed on this board (Lon's first link above), Miles got royalty payments from Dragon and thanked them for it; I don't think that would have happened if the release had been illegit.
Why don't copyright holders stop Amazon from selling PD material that shouldn't be brought into the US? Sometimes the fight isn't worth it. Just because they haven't stopped this release doesn't prove it's legit, esp. if it just slipped under the wire for PD status in the EU.
As I indicated a few times the Dragon set was released when the material wasn't yet in the public domain in the EU, that's why I specifically mentioned it. Why would they have paid Miles and why would he have thanked them if the release had been illegit? Did you read the discussion on this board Lon linked to above?