Goole and Yahoo, why don't they index the ID3 tags?

I am still wondering why an audio-search using Google or Yahoo doesn't really work. When I am searching on Marco_Raaphorst_-_Blowing_Snow.mp3 most search-engines are showing no results or will match that audio file with a page which is not the music-page of Melodiefabriek.nl for example.

Those search-engines seem to be using only text-indexes. I am wondering why they are not indexing ID3-tags.

Maybe because of copyright issues? I can imagine The Big 4 (Warner Music, Sony BMG, EMI and Universal Music) getting real nervous when Yahoo and Google start indexing ID3-tags. A simple search on 'Rolling Stones Miss You' would show links to mp3 and ogg files. But for open content material this feature is most wanted. At the moment searching for open content material doesn't work perfectly. Sure webpage's are indexed, but the real content can not be found easily.

Are these copyright issues the reason why Yahoo and Google are not indexing on ID3-tags?

What do you think?