I can only assume it has changed a heck of a lot in the last 25-30 years, even in the past 15 years since my departure.
Back in the early 90s, when the mask art craze was kicking into gear, the Pinnacle trading card folks saw a value in the art, and knew right from the start, that they had to recognize and compensate the artists for their work, for a 6 card chase set, for that year's card collection. That relationship went on very well, for a number of years. There were a couple of sizes of miniature, anatomically correct masks that they, and EA Sports were involved with, that also required the artists' participation, and we were compensated for that as well. There were those types of deals that continued throughout most of the 90s (EA Sports '94, McDonalds, etc) and everyone was well respected, appreciated the cooperation, and seemed happy.
Then, along came one trading card company decided to be a little greasy, and put out a mask chase set of their own, without the cooperation, nor the compensation. It got pretty ugly, ended up in the courts, was settled to our satisfaction, and that's when shit hit the fan.
Remember when getting ahold of a game used mask or jersey was something special - well, even more special than it is today? It was (coincidently?) around that time, that someone further up the food chain (seeing the opportunity to harvest a few $$) tried to grab ahold of this area and put holograms on everything, calling it an 'official collectable'. It was around that time also, that I stepped away from hockey, and lost touch with the process.
I've only heard rumours about the chain of custody now. Who is allowed to paint? What is allowed to be painted? Who has/had/signed away the copyright? I'm not sure. One thing I am sure of, is if there's even a whiff of $$, it'll cause a feeding frenzy, usually with those who had nothing to do with the process/design/finished product, being the first ones with their face in the trough.