In some ways this isn't as bad as I thought it would be. If you lead a union for professional athletes getting paid hundreds of thousands of dollars I'd expect the president's salary to be comparable, and my only real issue is with the unions for laborers who aren't making nearly as much as athletes. But even then, $300-400k is a reasonable amount of money for leading a huge organization. I am still vehemently anti-union for their ability to stagnate an industry and general failure to protect employees to the extent that they promise, but I don't find most of those salaries unreasonable for the size of their organizations. There are plenty of non-profits paying their leaders unreasonable salaries:
http://www.huffingtonpost.com/2013/04/08/10-insanely-overpai...