Merit Pay: What are they paying for?

I don’t really care if merit pay increases test scores or not, because I don’t think test scores are a measure of what education is all about. Still, if they do not raise test scores, as this report states, then why are they paying? To bust the union? To pave the way for privatization? To reduce teacher salaries? All of the above?

http://www.edweek.org/ew/articles/2010/06/01/33tap.h29.html?tkn=OPUFqM7io65bEbtpQ7Pp49tT3Bvei1BazDMp&cmp=clp-edweek