Hi, I'll jump in here for some additional clarity. (Hi Kentaro Sato, nice to see you here!)
The music industry worldwide does not have great methods in place for royalties in buy-out situations. For example, a lot of AAA game soundtracks, or those composed by in-house composers for game studios, are buy outs, and this complicates many licensing flows.
However, outside the US, music rights are collectively managed. In Japan, Germany, and elsewhere, mechanical royalties are paid to PROs (Performing Rights Organizations), who collect and retain those royalties. It is the responsibility of rights holders to come forward, register their songs, and claim these royalties. Claiming periods also expire, so in some countries, if rights holders are negligent and do not claim their royalties, the royalties expire after 2, 3, 5 years.
Most DIY distribution companies do not allow territory carve-outs. Professional label distribution companies do allow this.
Yes, Amazon and iTunes are directly responsibility for many rights. They need to have licenses in place with PROs, publishers, and other legal entities to be able to sell or stream music in each territory. For example, LINE Music does not have licenses in place with rights holders in the United States, and therefore cannot stream music in the US yet.
[*]Publishers and rightsholders are responsible for claiming and collecting their rights, delivering catalogs to appropriate agencies, and making sure they are paid for all uses.[*]In all cases is it appropriate and sensible to ask composers and rights holders for licenses. Unfortunately, not many game companies are interested in licensing rights to individuals, do not have an understanding of the music world, or do not have time to fulfill their obligations on an international level.[/LIST]
It is indeed a very complicated world. I have extensively spoken at panels and tradeshows, and have spent the last decade educating the video game music community on these rights, in the hopes that more composers are paid accurately and fairly.
( If any of you are at GDC, come to my panel on music rights!
https://schedule.gdconf.com/session/...t-panel/860237 )