The "cobbler's children" is probably a great topic for a blog! I too worked for a (very) big relocation company... I can relate to your experience! In the past, expatriates made a lot of money- that is changing fast. The growing phenomenon is "localization" and increasing difficulty in getting people to accept assignments.
I've been involved in the relocation business in the United States for many years. My experience suggests that the big companies make sure that their expatriates remain "whole" - they don't want them to gain, or lose, from the compensation perspective. There is strong infrastructure to help keep companies fair and up-to-date in their practices. They know that expatriates share their salary stories! Maybe your experience relates to a company that doesn't really value the expatriate experience and the role that expatriates could - and should - play in their global strategy?