Also not only would they need more satellites, but satellites more densely in any area with multitude of customers. Which eventually hits RF interference saturation.

Radio signal has only so much bandwidth in certain amount of frequency band. Infact being high up and far away makes it worse. Since more receivers hit the beam of the satellite transmission. One would have to acquire more radio bands, but we'll unused global satellite transmission bands don't grow in trees.

Tighter transmitters and better filtering receivers can help, but usually at great expense and in the end eventually one hits a limit of "can't cheat laws of physics"