Just 158 families dominate U.S. presidential campaign contributions: http://nymag.com/daily/intelligencer/2015/10/158-families-do...
Inequality is not only about money, it's also about influence.
Single payer health care is a good example.
We should strive to avoid dogma and choose the best available solution.
[1]http://www.cbpp.org/research/romneys-charge-that-most-federa...
E.g. that chart says that ~96% of Medicare spending went to beneficiaries. That sounds good, but all it means is that 96% of the dollars were paid to hospitals/doctors/medical device manufacturers/etc. It says nothing about how efficiently those people are providing their services, i.e. how efficiently those 96% of Medicare dollars are being spent. A lot of those dollars get quickly chewed up by high prices (which I'd argue are themselves caused by the market distortions that these programs foster).
Government expenditures stay the same but rich people pay more and poor people pay less.
There's often an assumption in these discussions that if a billionaire isn't spending their money in a socially optimal way, the government will spend it better. But if you look at how governments actually spend their money, you'll find very little evidence to support that assumption.