Warning: contains spoilers for Joker #2!
DC just revealed why Batman has never been able to track down Joker until he's perpetrated a crime or until the Joker wants to be found. What's worse, the reason why the Clown Prince of Crime always remains elusive could be because he's getting help from some of the most influential people in the DC Universe.
Commissioner James Gordon reveals this unfortunate truth during an internal monologue in The Joker #2, written by James Tynion IV and Sam Johns with art by Mirka Andolfo and Guillem March. The owners of various luxury getaways around the world have apparently hosted Joker at least fifteen times, free of charge, as part of an underground operation known as the Network. Those who have hosted Joker without Batman finding their esteemed guest can then boost the price of their properties and advertise to potential clients that not even the Dark Knight could root out their premises, promising the coveted seclusion and privacy that their clientele crave.
Joker is currently hiding out at such a resort but, unfortunately for him, is no longer welcome, after having killed one of his host's wealthiest neighbors. Despite this misstep, Joker is able to convince his host to graciously elongate his stay by promising to protect his property, which is ironically the target of various criminals who have learned of Joker's whereabouts and are coming to take him out for his supposed attack on Arkham Asylum.
The introduction of the Network to Batman's universe not only adds yet another layer to the already vast pile of corruption that has been infecting Gotham for decades, but provides an additional example of how far humanity will sink to make a buck. That's because it seems like the Network isn't a purely criminal enterprises, but includes numerous people who have agreed to participate in illegal dealings to help boost their legitimate businesses, possibly including politicians. The fact that the Network advertises every time they have shielded Joker from the likes of Batman means that their clients are aware of these transgressions and have never alerted the proper authorities, indicating an entire web of corruption that has helped to keep DC's deadliest serial killer safe.
Despite making it clear how complicit supposedly normal people are in Joker's crimes, the more about the villain that is explained, the less mysterious - and arguably more human - he becomes. Part of what makes Joker such an intriguing and effective character is what isn't known about him (which is a lot). Revealing why Batman has only ever been able to react to Joker, rather than hunting him down before his next atrocity, makes the Clown Prince of Crime less of an enigma. It defines him, and Joker is meant to be undefinable. Even though Batman might never unlock the secrets of the Network, the fact that he could means that Batman could become proactive, and that would destroy everything Joker represents.