Pandora blocked for Canadians

[FartinMowler]

We are deeply, deeply sorry to say that due to licensing constraints, we can no longer allow access to Pandora for most listeners located outside of the U.S. We will continue to work diligently to realize the vision of a truly global Pandora, but for the time being we are required to restrict its use. We are very sad to have to do this, but there is no other alternative

Why is this exactly?