Rhys, I dont know what to say to you, you obviously must go around wearing your tinfoil hat because you seem to think that every organization, credit card company, bank and everything else in this world is out to get you.
I have multiple bodies and I have plenty of cash reserves to go out and buy a duplicate of every piece of equipment that I own if I needed to.
However, I dont have to because I am a member of CPS. If I have a camera break on a job, I can have a loaner to me the next day via FedEx. Of course not always if they are all loaned out (like trying to get stuff during the World Cup and Super Bowl are hard as most of their gear is out on loan), but they come through more often than not.
I had a friend have a shutter blow at an event last month on his MkII. He had a 1D in his hands the next day from Canon, sure not a MkII, but another very capable camera.
Its a valuable resource and its FREE if you qualify. There is no reason NOT to join if you can. Why not get a discount and expedited repair? Why not have the ability to test a new lens for free if you are thinking of buying it? Why not be able to possibly get a loaner if your camera goes down? Seems like a pretty simple question to me.
As to why they keep it hidden, well they dont exactly. But its more of a word of mouth thing in the US. They dont want everyone and their mother applying when most wouldnt qualify, they count on pros telling other pros about the service. They are more than happy to send you the paperwork if you simply ask them.