Bruce has quite a large network of NPCs. There are the people he employs and his shareholders, all of whom he goes out of his way to remember personal details about. He's also familiar with a lot of the competition and other high-society types.

Batman has his own network on the streets and is one of his main sources of information. Anyone who knows how to know a little of something and are willing to share, basically. A lot of the worst off get referred to entry-level jobs at the Laskin Corporation. He also knows a lot of NPC cops.