The unintended consequences of self driving cars?

Nah. The unintended consequences of the commons - ie subsidizing public roads. From Wired:

As driving becomes less onerous and computer-controlled systems reduce traffic, some experts worry that will eliminate a powerful incentive—commuting sucks—for living near cities, where urban density makes for more efficient sharing of resources. In other words, autonomous vehicles could lead to urban sprawl.

It’s simple, says Ken Laberteaux, a senior scientist at Toyota. If you make transportation faster, easier and perhaps cheaper, then people won’t mind commuting. “What a consumer is expected to do is see what they can gain by moving a little further from the job centers or the cultural centers,” he says. That’s bad news: Urban sprawl is linked to economic, environmental, and health hardships.

As usual though, it's elites who seem to be wringing their hands over the poor(er) improving their lives in tangible ways.