In Batman begins, the issue is corruption.

Everyone knows Falcone is guilty but no one has the legal ability to arrest him.

So Bruce Wayne becomes a vigilante in a more Luigi kind of way in which he is willing to risk things cause he has the tools to do it right.

The whole point of Batman is doing all he can with his resources, even if that means breaking the law.

But yeah, we know today that the most effective thing he can do is not even charity, but pay for lobbying