Before raters started paying to be raters, one could make the argument that their motives aren't clear. With them now paying for their access and their freebies, it's clear that the magazines are selling them something, so the volunteerism possibility is pretty much out the window at this point. The conflict for the magazines is irresolveable: they're in the business of usurping value from the very same courses they write on in their publication.
I would like to go a bit against the notion that it's "clear that the magazines are selling [panelists] something" if I may.
The print publishing business has changed a bunch in recent years, in ways of which I won't pretend to have expert knowledge. But I think it's conceivable to speculate that magazines' operating budgets have changed, such that it would seem conceivable that the golf course ranking departments have needed to become self-sufficient. It costs money for these editors to administrate these panels and produce content around the ratings, so what's nefarious about them generating the revenue to operate them through the panel?
It's certainly possible that these publications break even or better from this enterprise, but it doesn't make their relationships with the country and world's great courses purely parasitic, as you seem to be arguing. It's demonstrably symbiotic, as courses have benefited from the exposure that rankings bring.
Why don't you think these clubs are capable of calculating the opportunity cost of refusing to continue comping raters, or even soliciting rater visits at all? Are these great clubs run by idiots? I don't believe that.
Also, on the comp issue, do you think people who aren't financially able to pay hundreds of dollars a number of times over, per year, should be automatically disqualified from being able to contribute to the evaluation of golf courses? It seems that a lot of people's careers in golf have been sparked by golf courses choosing not to charge them to play.
Again, I'm not arguing that the rating game should be all-free, because that's a level of entitlement I don't hold. But I think there's a spectrum of ability to fund the "rater's lifestyle" (don't hurt yourself rolling your eyes), and I think it deserves some consideration.