But I disagree that there is very little income mobility. I found there is quite a bit of income mobility. I was making just under min-wage... hmm 10 years ago. Now I'm making more in a week than I did in a month before.
Your anecdote does not trump statistics. Inter-generational income mobility is the standard measure, and in the US roughly 40% of people born to the top or bottom 20% will stay in that bracket. A country with true mobility would have a 20% chance of staying in any 20% bracket, and countries like Denmark and Norway come pretty close to that.
The US ranks behind France, Canada, Germany, Norway, Sweden, Finland, and Denmark in income mobility. (And those are just countries I have stats for. The UK was the only country worse than the US in the numbers I've seen for developed nations.) The US is less "the land of opportunity" than much of Europe.
That said, your experience with part of the problem being cultural seems spot on. Not all the barriers in the US are imposed from the outside of people, and there is some rather rank class envy that our inequality has helped foster that turns to excuse-making. Those attitudes do nothing to help people any more than any other form of resentment.