How do copyright laws differ between podcasts and broadcast radio? Wouldn't the rights need to be acquired anyway to put it over the airwaves, or is there some fundamental difference between how things are handled on radio vs. the internet?
I think streams where you don't pick the song that comes up next can also be licensed more similarly to radio broadcasts.
The law itself isn't really the question here; it's more the economic entities and standard agreements built to sustain broadcast use of music can't be adapted to podcast use in a cost-effective way.
This is also why we don't have the Massive Attack song as the intro to "House, M.D." on streaming services any more.