Public defender offices are funded by the state and they are terribly under funded.

http://www.abajournal.com/magazine/article/the_gideon_revolu...

Because not much political upside to helping criminal defendants exists, many jurisdictions end up with a perennial funding problem ... In both cases, the committee heard about extreme funding shortfalls, excessive caseloads and insufficient pay.

After years of cuts, his budget was down from $9 million to about $6 million, and he had just eight investigators for 21,000 cases per year.

This matters because the majority of defendants—a 2014 study put it at 80 percent—use some kind of indigent defense. That means most Americans charged with a crime are at risk of bad outcomes partly caused by the quality of representation that they can afford.