I coded up an MVP and we got a few customers that agreed it was something they would pay for, as long as they had a decent chance to make even a small profit on song requests.
Once it looked like a viable product idea, the financial numbers guy did his magic and researched more details about how royalties worked.
We got conflicting information from different lawyers and royalty aggregators. After a couple months of research we determined it was completely impossible to make a profit, until we hit maybe 5 million in revenue and could start to negotiate better rates with copyright holders.
This assumed extremely cheap tech and bandwidth, and almost no salaries for us three founders.
We killed the project because it became clear how sadly broken the music industry has become. They wanted about 50% of our revenue, no matter how we sliced the business model. We are totally miffed at how pandora or spotify survive.