Income and education by zip code: with a massive flaw

This is a great interactive chart:  you can find out the income and education level vs. the rest of the US for any zip code.  But it has a horrible flaw:  there is no adjustment for cost of living.  The result is the Northeast looks far richer than it really is.  The brutal truth is that real per capital income is higher in Oklahoma or Alabama than in New York State.  A reality that this chart completely misses.  Indeed, I wonder how much of the so called 'income inequality' in the nation is spurious, reflecting the fact that lots of lower income people live in lower cost states and vice versa.  Hmm, I'll have to noodle on that one.