It's just different values. I could ask the same about the US and nudity. In German media, blood and violence is fine, but it's considered a topic that you need to be able to handle, so you need to have a certain age, depending on how gruesome that is.
Tbh, I'm European and therefore biased, but the way the united states have no problem with people harming other in media but being offended by something like "bodies" or "sex" does seem a little weird. Like, if my kids normalised harming others I'd be much more concerned than if they normalised making love.
So... What are those two stars for then?