I'm never really sure how to deal with it. There's a lot of things like that I encounter with anime, and a lot of times it's other things I find really offensive too. For instance black face and other seriously racist humor come up in places I wouldn't normally expect like the Shaman King or Cyborg 009 or even stuff like One Piece and DBZ, not to mention the stuff you mentioned with sexualizing underage characters.
Generally when I encounter something like that I simply stop watching the series. I don't know enough about it to say pedophelia and racism are more acceptable over there, but it's not really something I'm about to subject myself to under the guise of cultural sensitivity either.
Every country has sick, offensive shit that is labelled as entertainment, I guess, but that doesn't mean you need to refrain from calling it out when you encounter it.