Yes, voluntarily. People would kill to get these ostensibly terrible recording ontracts. Because, statistically speaking, the alternatives for artists are to 1) starve to make their music or 2) get another job. Playing live does not make real money to any but the small fraction who are already famous, and guess how they got there in the first place!
You are totally right and I couldn't agree more with you. The thing is that the record companies have created an environment where almost the only way to make a living is signing "voluntarily" with them.
Nowadays a musician is not so different from a software developer. They can work solo or in groups, they can distribute their songs freely or decide to charge for them. But the software developing world and the music world are two completely different worlds when you look at the business model. So yeah, you can voluntarily sell your software to a giant like Google or Microsoft, but I'm not sure that signing for Virgin or Warner is such a voluntary act.
Doubt Kim's service pays anything to the artists at all.