The AMA Nats currently charges $10 per event for all CL events except CLPA (stunt) which charges $45, presumably to pay judgers and other workers. So the idea isn't all that new. Obviously, a goodly number of people accept this tariff.
In the previous years, I've flown just about every catagory, except stunt, due to this fee. CLPA got along just fine without my $45. Maybe keeping casual "fun type" entires out is the plan. If so, it works.
In Combat, Speed, and Racing, I pay $10 and expect to take a turn judging while I'm not flying or pitting. The four ability groups in CLPA do an adequate job of providing a pool of judges who aren't involved in the group being judged. I guess if somebody wants to try running local contests with a Nats-style entry fees and paid judges, they're free to give it a try.