Tom,
My information is old, but I don't think so. I had the impression that most were of some means, like airline pilots who traveled anyway.
If it were a requirement, I suspect this group would start arguing whether there should be a quota for public golfers, or a floor and ceiling as to how much dues the private guys paid, etc.
I mean, for those who don't like the GD system (read that anyway you want) there is no end to what they can find to criticize.
What I don't really get is the debate as to why GW is better. Brad basically patterned his off GD, but obviously wanted to make his different enough to justify/differentiate two magazine lists. It's still points, with slightly different, but mostly overlapping criteria. You can make the argument that his list, as the second stab at it, is a bit better, and that GD perhaps felt like they had to stick to their original legacy lists for consistency, but big whup. They are both trying to get to the same place.