> Income mobility in the US hasn't changed. This is the strongest counterargument to complaints about income inequality leading to unfairness I am aware of.

It's not because it hasn't changed that it's fair and can't be improved.

> America was a country where opportunity made it so you could become wealthy.

"Several large studies of mobility in developed countries in recent years have found the US among the lowest in mobility"

http://en.wikipedia.org/wiki/Socio-economic_mobility_in_the_...