Originally posted by Dave K
Unfortunately, it's not that simple.
Artists very rarely own the rights to their music. Their labels do. And they all operate separate entities in separate markets to deal with the fact that each market has their own copyright and contract laws to deal with. Because of this, signing, say, WB US does not give you access to WB UK catalog. You have to turn around and sell WB UK on the idea and negotiate another contract under UK law to sell their catalog.
Then you get into fun things like local content laws and differing tastes and suddenly WB US's catalog differs from WB UK's catalog. Either because release dates are different, or WB UK/US doesn't think the artist will sell in their territory, so they don't obtain the rights and that artist is simply not available. Then, you have to sort out whether or not they've signed locally with someone else, or do you need to "import" that artist from another zone and who the primary rights holder that has to be paid for the privilage is. Which is why, for example, when I went to hunt down a Warren Zevon album for my dad last christmas, his early records could bought for the local going rate, but most of the newer stuff put out since his fame died down had to be bought at as an "Import" at twice the typical local price. No local distributer wanted it.
That's just one of the ways the entire process could best be described as "legally messy", even before the Labels start tossing their own extra conditions into the mix...