The root cause of this is the simple fact that SJWs and Liberals in general are literally incapable of forming a theory of mind for centrists (normal people) and especially 'conservatives'. That is to say, that can't see the situation from another viewpoint even as a purely intellectual exercise. Worse than that, they can't even
conceptualize having any viewpoint that isn't their own.
This has been demonstrated through some interesting studies where people were sorted into Liberal, Moderates and Conservative groups. They were given a moral question survey, and asked to complete it three times; once honestly as themselves, then again as if they belonged to the other groups. Moderates and Conservatives were pretty accurate at predicting how the others would answer, but the Liberals were completely off base for both.
As a group they cannot conceive of a "theory of mind" for conservative people. They are unable to even fathom that people can think in ways they do not. Hence their inability to consider that anyone thinks differently or has other moral codes. Not just American conservatives, either, this also accounts for why they are so incredulous about, for example, 'migrants' not respecting the law and raping women and robbing and such. The Radicals simply can't imagine that a Somali-raised brain holds a different worldview.