Corporations get to be treated as human beings in a court of law, but I guess not when paying taxes ... or with psychological diagnosis for that matter(psychopaths). But the whole taxing issue seems like a complicated problem - I've read that 2/3rds of U.S. corporations are able to avoid (most, if not all) taxes, and that they do this through legal loop holes. It seems like raising the tax, even just to pre-bush-cut levels, would give incentive for even more businesses to waste resources on tax avoidance and to declare their base in some other country with tax havens. Closing these loopholes, I've read, is nearly impossible, and would also lead to more business leaving the country. Also, if we raise taxes on the corporations, they are just going to spend major money next election on whichever official will cut the taxes back again (thanks to that supreme court ruling last january).
For me, the most interesting point to note on this graph is how often recessions / falling GDP seem to line up with war, and how a lack of war often lines up with a lack of recession.