The major DSPs in the music space have to license each music company separately. YouTube, Amazon, Soundcloud, Spotify, Apple - all have individual dealings with the majors and with groups of or individual indies. It's definitely not as simple as requesting a blanket license for all music everywhere and paying a single fee.

Sure, there are three major music companies and six major film studios plus a bunch of major tv networks / distributors but it's still a long set of negotiations.

I think the difference is that the music companies understand the value of each service having ubiquitous access to every piece of music. UMG's decision to stop their artists agreeing exclusives with single platforms demonstrates this to some extent.