[ApK]

Can someone please help me understand something about Prime Music and the Echo:
As Prime members, going to the Amazon music website (and presumably the Music app) we see several Adele albums, which we can play freely, choose to play specific tracks from, and download to the device if we like. But when we ask any of our Echoes to play the same songs or albums, we just get the "only with Unlimited" sales pitch. If we make a playlist with those same albums or songs, and ask the Echo to play the playlist, then she'll play them.

What's going on? Shouldn't the same Prime music content be available via Alexa as via the web or app?

TIA,
ApK