They’re not the only ones making that media, right? Or do they make the media for everyone and put other names like Memorex on the label?
Don’t the other companies still have to license or at least pay royalties to Sony to make BD-R or that only for commercial discs?
No. Sony was one of 9 companies that started blu-ray in 2002. There are more now that can license production of it.
https://www.sony.com/en/SonyInfo/News/Press/200205/02-0520E/
Unless I’m mistaken, and I probably am, the patents on blueray should have expired by now. Software side might be covered under copyright right though. Not sure if software can be copyrighted though tbh.
For now.