But…really? No critical thinking?
It's quickly stomped out by groupthink. Other people point to lack of education, but I don't think that's correct. They are surrounded by Republicans. All their friends and family are republicans. Most people in their towns are.
Going against the group means being ostracized. They see the amount if hate and vitriol being cast at the others and they are terrified that it will be cast at them. So they always go along with the group, never against it. They can think critically but they won't ever do so out loud.
Look at how even some far right people have been painted as liberal hacks by Republicans just for not being far right enough.
They are absolutely terrified that will happen to them.