I haveb’t looked into this particular group, but usually it’s patents. Someone owns a patent for the tech required to implement the standard, and they “license” it out to anyone who wants to implement that standard. Obviously, they won’t agree to terms that hurt their ability to collect rent on their patent. Qualcomm is famously guilty of this in the modem space.

Does that seem stupid, to adopt an industry standard that requires patented technology to implement? That’s because it is, and were we a sane society we would invalidate any patents that become an industry standard, but we’re a bunch of idiots with a billionaire cuck fetish.