[g_h]

Dwolla did not perform a "background check" in the sense that you may think. When dealing with online fraud, it's common to use identify verification services like IDology (and a few others) that basically provide an API to generate these types of questions based on public records matching your name/address. Many banks use the same verification services.

[Xorlev]

This. Experian provides the same service, it's usually ~$3/pop if I remember right. This gives you those "Did you live with a Paul Foo at 378 Combinator Way from 2006-2009?" questions.

[unclebucknasty]

Odd, because if it's publicly available...