Got any more info on all this? In Canada being an independent contractor means you can go HAM on tax loopholes so with a good accountant you're pocketing way more personal cash than a regular employee all the while still keeping your actual "business" healthy in the black.
Of course I can't pretend to know what medical insurance in the States must be like to pay out of pocket

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You can also go ham with tax loopholes as an independent contractor down here. The issue comes in when it comes to getting injured, and accepting bookings with other companies.
Since the WWE only insures their top guys, everyone else is paying out of pocket when they get hurt. They suffer financially since they are only paid their downside guarantee while they aren't on the road, along with whatever royalties they are owed from merch sales and any checks they haven't received for work they've already done. I don't know if WWE pays guys on a net 30/60/90 basis. I would imagine its on a net 90, since their contracts keep talent off tv for 90 days after leaving the company unless they give up that money in exchange for the ability to accept TV/PPV bookings.
When it comes to making appearances in other companies, the answer to that is pretty much hell no, not while you're under contract. Back in 2008, Robbie McAllister of the Highlanders attended a TNA iMPACT show (it was Wrestlemania week, they were in Orlando) while under contract with the WWE. TNA put a camera on him and used his real name. Someone spotted this, called him, and told him to leave immediately. He was fined his WM payday and released 5 months later. Granted, they were jobbers, but that's still a bit harsh for doing nothing more than watching the competition live and sitting in the crowd like a civilian. There have been exceptions made, but usually as a favor to someone or in case of an extreme emergency. CM Punk worked an ROH match while he was in WWE developmental because of a snowstorm that prevented half of the booked card from showing up.
IIRC the judge in Raven's lawsuit said that the case had merit. Raven, Mike Sanders, and Kanyon (?) were all guys who hadn't worked for the E since roughly 2002, and the suit was filed in 2008. None of the current workers want to be that guy who rocks the boat and ends up getting blackballed by the E. Everyone bets on themselves to rise up to a level where they can negotiate deals like Orton/Cena/ADR.