Those are commercial arrangements. I was an artist lawyer for almost 15 years. In the case of the singer-songwriter, you would sign a record contract. The record contract would spell out royalty provisions, copyright, the amount of money that would flow to the artist, and what the artist is giving up. It's a commercial exchange.
It would be the same thing for a publisher. A publisher works specifically with the songs, not necessarily the master recording. Again, you would find contractual relationships that would dictate how the money flows.
Today, we're talking about remunerative rights. All of these remunerative rights benefit artists equally: fifty-fifty with labels. I think that's particularly important. Also, with the rise of the artist entrepreneur—the artist who owns their own master recordings—sometimes they have 100% of it.