Well, that's an interesting thought for sure and it's something linguistics and philosophy focuses on - the arbitrary nature of boundaries/categories and what's salient and why.

There's a good book called Neurolinguistics and Linguistic Aphasia that talks about salience to different people. It makes a soft argument that perhaps everyone has synesthesia, but we all repress it to some degree (unless diagnosed with the actual synesthia condition). And different people have different types of synesthesia. So we are all experiencing and categorizing differently.

Then we have life experiences and trauma on top of that. Many times people focus on particular groups because of systems, perceived or real, within those groups that affected them. Sometimes it's not even a real experience, but instead trauma from parenting that is triggered by the metaphor of these systems. They are mainly worried about safety and security, which is often why the group they hate is simultaneously weak and powerless while also being horrible and the worst and extremely deadly.

When you combine those two, you can see the drive for their stereotyping (desire for safety) and what they find salient to criticize. Ignoring the nonspecific value statements (eg bad, stupid), and focusing on more specific criticisms can help you suss out what's actually being disliked and if it's related to a sensory thing, trauma, and/or rational criticism.

"They are awful. I hate soldiers. They burned my village. It smelled like smoke. Whenever I see someone in camo, I smell smoke that tastes like death and cooking bodies."

The above person has gustatory-olfactory synethesia and that's how their brain triangulates their memories, along with sight and emotion. They may even KNOW not all soldiers will hurt them or burn down their new house. But they have these mental and emotional patterns that automatically get triggered. They've likely based a lot of their mental scaffolding on that. To suddenly change their mind isn't physically possible because it takes neurochemicals to change mental pathways and it takes time. Just like I can't deadlift 300lbs immediately because it takes time to grow those muscle cells enough to do that.

Some people don't have any energy, neurochemicals, or time to change their mind. Some people are living desperately and can only focus on so much. Being humble enough to self analyze and improve yourself, being brave enough to deal with the fear and pain of trauma, is a lot. We also all have blindspots and aren't all perfect.