TO,
One thing you don't mention in your post is that recruiters, when presented two candidates otherwise 'equal' - one with a college degree and one without - will almost always choose the one with the degree. That factors into income statistics. If I were the college recruiter I would do the same thing. College also teaches analytical thinking (well they are supposed to), which also factors into income, as those moving up corporate ladders are more typically rational, analytical thinkers and planners. There are a lot of other reasons to get a college education that don't necessary factor into income, such as personal growth and being exposed to many different viewpoints, thoughts and ideas.
Additionally, unemployment rates in the US for college graduates are typically half those without a college degree, and that 'statistic' remains fairly constant during recessions and boom times. That also factors into income.
Dubs and ex-dubs: go to college. Professor DJS says so.