"He could not envision that poor whites and former slaves had more in common with each other than they had with white elites. Things have not changed much."
We were in S. Africa for 5 years during the worst period of apartheid. There are many similarities, and the fact is that everyone (white, black, brown, yellow, mixed...) colluded with the system at some level; denial was rampant; good people could not see their own collusion (I do not say this in condemnation). One of the MPs said, "It is easy for liberals to criticise; they buy their separation. Poor whites are the ones who need protecting" or words to that effect. 
There are many similarities in US. Until we walk in the 'other's' shoes we will have little compassion  .. all of us need compassion and mercy in real life. It doesn't matter how much we understand intellectually; we need to engage at a visceral level with what people are experiencing and what they are afraid of - not only sit in judgement which is mirror-imaging.