So you looked for evidence to support your a priori beliefs, didn't find it and still made insinuations. Good on you.
1. Comparison of Harvard tuition to prisoner's costs is meaningless as done in the article
2. The article itself mentions costs raise mainly because of labor costs
3. The article itself mentions that drop in the inmates number did not reduce labor costs
4. The article does not mention any of the factors influencing labor costs.
Which evidence you think I am missing?