Why don't they...?

I'd really love to write a longer piece on this, but for now I'll leave you with this burning question (and please do feel free to add your answer, if you can enlighten me)...on the radio (P3) this morning I once again heard Slave To Your Charms by Kind of girl as well as Told Her I'm From Compton by The Floor Is Made Of Lava. Why don't they ever inform the listeners that the songs are actually legally available as free downloads at Myspace, Last.fm etc.? Wouldn't THAT be great service?
+ Slave To Your Charms
+ Told Her I'm From Compton