no, this is not true at all. it's not a matter of "I want to raise my friend's salary and he'll raise mine".
silly conspiratorial thinking like this is just a waste of time. it's defeatist, and when examined will be easily defeated in an argument.
the real reason is very simple. boards consist of large shareholders of the company, representatives of large shareholders, and usually a few other trusted advisors.
their objective is to make sure that they pick the right management, and guide said management in making the right key strategic decisions, so that the shareholders' stake in the company increases over time.
these boards believe strongly that the CEO is the single most important person in the company. which, more or less, is true. a good CEO is an amazingly powerful force in shaping a company.
boards are weary about people who haven't proven themselves, because a lot is at stake. so they have a limited pool of candidates to pick from.
every board is trying to pick from that limited pool of candidates.
as time goes on, the bidding wars for these executives has gone up and up dramatically. people see 1 sign of success as somehow indicative of a person's ability to lead. this is obviously not true. inexperienced people may still make for exceptional leaders, exceptional CEOs.
but the culture is to stay the course. pick someone who has won at least once before because they know what it takes, that's become the conventional wisdom.
hence pay has increased dramatically. there's no backroom dealings where people sit around and discuss salaries and bonuses.
in fact, boards compete in bringing on top quality management - that naturally drives up the price of a CEO.
I've seen this time and again, I worked at an investment bank. your investment would be poised to bring on a new exec. then all of a sudden, he's offered a lesser title with substantially higher salary at a different company.
well shit. what do you think he's going to do? he's going to come back and ask that you at least match him. or you give him some kind of special bonus, or massive options, etc.
I'm not sure how corporate governance is in other countries, but I imagine its a little bit different than in the US. The CEO of nissan was japan's top paid exec. He earned $10m. Which is a full order of magnitude below top US execs. and keep in mind, carlos ghosn is a legend in the auto industry. he is a complete badass.