I'm guessing you aren't conversant with how taxation and class mobility have changed over the last 40 years. Let me save you the suspense: you're wrong.
Marginal tax rate in the US has fallen like a rock since Reagan got into government. The exact same time class mobility went down as well. If you look at the statistics class mobility is highest in high taxed Nordic countries. Low tax anglo-saxon countries are usually pretty bad at this. The UK follows much of the same ideology as the US and also has among the lowest mobility in Europe.
It is nothing weird about this really. Higher taxed countries are able to offer better public education and health care which gives the lesser of actually stand a chance of making it.
In the US the system is especially rigged. There is no free school choice, so you are forced to go to the public school in your shitty neighborhood if you are poor, while the rich through never ending donations enjoy schools with abundant resources. And even if the schools were good you would be screwed before you even get in, because the US does not offer quality child care to poor people. Research shows the years before school is the most important for future development.
I live in a poorer area of Oslo, but I could if I wanted to send my kids to the schools in the richest part of town without any extra cost to me. But it isn't really important as school quality is pretty even, through proper public funding rather than relying on private donations. Also we get subsidized child care of a quality that typically only upper middle class buy in the US.
If you don't even the playing field in a persons early years you are not going to see much social mobility.
