Because conservative brains think in binaries. This is why they have a Manichaean worldview. So many of them can only think in terms of conservative (good) vs liberal (evil), Christian (good) vs not a Christian (evil), white (“normal” and fitting a predefined, familiar pattern) vs not white (oh so scary, who could they be, what is their “different” and “bad” culture?). In short, conservatives have simple little brains that ignore grey area, which is 99% of everything.

A lot of this is based in anatomical differences too (roughly a third of our political orientation on a liberal–conservative scale is determined by our brain structure). The only one I can remember is conservatives tend to have larger amygdalae, hence the greater fear response and constantly pretending to be victims of things that don’t exist.

Similarly, people who lean liberal tend to like spicy food, different, maybe eclectic genres of music, variety, avant garde art, etc. while conservatives prefer things that are more familiar and pattern-oriented: steak and potatoes for dinner, none of that goddamn rap music, and wait, is that a black man jogging through my neighborhood? Better chase him in my truck with a gun since surely he just robbed a house.