No I don't know the it's and out's of it either, but when you are in an information gap, you fill it with speculation as happens on forums.
I disagree with you on the reward thing. Kids are frequently told, work hard, train hard, play well, perform and the honours will come. To be picked for a national team in any sport recognises your ability and that you have demonstrated that. The only outlier is probably Wayne Gretzky whom is a difference being in the ice hockey field.
If you play well in Super 15, your reward is an AB jersey usually. Of course being picked for a national team is a reward or if you prefer a world that sportsman frequently use, a bestowed honour.
And the $2k?