Watch The Sopranos or The Wire. Crime needs an ignored working and poor class who find it more opportune to rob businesses and guard crime lords, than to try and work a cash register or scrub toilets.

The Venture Bros has an episode where they need all new henchmen and they try to hire some gang members off the street.

In the Harley Quinn show there is an agency for the top tier ones. The regular ones you can pick up at a bar. Kite man literally bursts into bar and asks if anyone wants to do a job but it depends on the weather and everyone goes with him.

Thunderbolts and Agent X both explore this a bit, and go for the dive bar angle.