In our society we don’t objectively consider it wrong, otherwise Batman (Superman, Spider-Man) wouldn’t be so popular.
"Law" is just another way of saying, "The bare minimum standard that we as a society will accept."
So when we have a society that sends a drunk driver to prison for 70 years for killing a family of four in a head-on collision, but we don't send people to prison for their lives for gambling with the pensions of teachers, firefighters, etc., for polluting the waterways and the earth itself, of course this is the ultimate, eventual outcome.
The only shocking thing to me about Luigi's case is that it didn't happen sooner.
Yeah I listed all of those because it’s funnier when people mistake the vigilante justice’ thing for a ‘not killing people’ thing and then I can trot out Clint Eastwood and Dirty Harry, which was so popular it gets quoted regularly and had four sequels.
So yes, batman in particular would be considered bad by most people. He is just another gangster cause quite a lot of damage to the city on the regular. We do not care, because it is made up movie city.
Superman and Spider man afaik do not go around randomly assassinating people, but it is a long time since I watched that.
Batman is the absolute opposite because he goes out of his way to avoid killing villains, even incredibly evil ones like the Joker.
Let's be real: the original super heroes avoided killing because children were their target market, and unlike with cowboys and outlaws or indians, it would have been unseemly by the standards of the time. Not because of some kind of big point about "just vigilantism."