MTS standard noise reduction was developed by dbx
https://www.broadcaststore.com/pdf/m...20-%205382.pdf
Receiver manufacturers were pissed at the exorbitant dbx licensing fees, but legal negotiations failed to get them reduced, so the major makers eventually paid them. Some companies avoided the license fees by simply eliminating the dbx circuit, but that meant that stereo separation suffered due to imbalance between the L+R and L-R signals, depending on the sound level.
Patent law says that the patent owner can absolutely deny the use of the patented technology to those who don't pay royalties, but standards bodies require any technology written into the standard to be licensed in a "fair and reasonable" manner. That word "reasonable" results in an opening for legal wrangling to determine what price is "reasonable."