It's very simple. The, DMV is the de facto conduit for all humanity, and every human being that we track down has a record in the DMV database. Whether it be LAPD, Social Services, the Credit Bureau, or the FBI, they all use the DMV's database as their hub. So, we have people on the inside who feed us the information.
And who would know it? The gatekeepers of humanity turn out to be a bunch of sassy black women.