Uhm, what? I think UK politics is pretty sane actually. It has a lot of problems, but definitely not this almost civil-war-like type of language that you have in the USA. And although the UK is getting worse and worse, there are European countries that still have a worse political environment.
I'm not sure that just the force of rhetoric used is a good measure for how sane politics is.
You can be polite, and still be insane or evil (see: Brexit and all of the politicking and --from what I can tell-- outright lies that were sold to people). That whole process was mostly civil and polite, but not necessarily healthy.
