First, I think part of the problem is that many people assume that any disagreement is equivalent to total disagreement. That is, if you don't agree with me on arbitrary position X, you must not agree with me that we shouldn't feed babies to hippos for sport either. Vocally disagreeing with Nazis is fine. Spiraling toward "people who disagree are Nazis" isn't.

Second, I work in tax policy. There is absolutely hate between many people who disagree on taxation.