Whats the reason the us has a politisized supreme court?

I am not american, as you can hear from my accent, but ive seen alot of politics in my 50 yo life.
How come the court sytem in the US is based on politics? It seems completely un-democratic snf i donty know any other country that has the same. People are wishing for RBG to die so they can elect a new one? Whats good about this system?

Our high court where i live, ive never ever known what political affiliation they have , unless they went into politics later.

It seems so wrong, so turn me right?

Closed duplicate.