Perché non posso votare sulle canzoni di iTunes Radio?

In base al documento di supporto Apple per iTunes Radio:

There may be some DJ-curated stations that you may not be able to modify. You can't like or play more tracks like this while listening to some DJ-curated stations. You can however, start new stations based on the current track or artist of a featured station or add tracks to your iTunes Wishlist from the Star (✭) menu.