With UCLA, I don't think it's that they hire alums as much as it is that they hire people who have no leverage to get elite-level compensation. Ricky N. was damaged goods when they hired him; he was just looking for redemption, not a top-tier salary. Same for Kelly, whose reputation as a genius had been bruised by his last year in Philadelphia and his season with the 49ers.
As for Foster, the guy was a position coach making $350K when they elevated him to head coach in an admittedly dire situation, thanks to Kelly. No way could he hold out for $6-8 million a year.
this is why ucla is big on bringing back alums like neweasel and radio. They can talk them into taking one for the team salary wise.