Originally Posted by The Joker
Ra's was different. Neither Gotham City or Gordon knew of his existence. Only Batman did. Everyone in Gotham is aware of the Joker. He made one hell of an impression on them. One that is still going to have repercussions in this.
The entire city was under attack by The League (with biological weapons), and they had to evacuate. They also said they infiltrated every level of their city. No reference at all of the massive attack or destruction from Begins in TDK is glaring.