That graph is very telling in how established classes are in countries.  We are down with the Scandinavian countries where there is little class structure.  Your socioeconomic status as a child has little to do with your ability to succeed.  I suspect this is because of social programs and strong public education.  Most people in Canada have a chance, no matter how they are born.  Most, not all.

Then you look at where the US resides.  The land of the free where anyone can succeed if they put their backs and their minds into it.  Not so much it turns out.  The oligarchy in the US is strong, established, and there are far fewer systems to help the poor claw their way out.