From the NewScientist (28 February 2015) letters section comes correspondent Martyn Thomas:
Changes in human behaviour may make driverless cars unusable. Why would you wait to cross the road, or pull out at a junction, if you know that the approaching cars are programmed to give way?
I’m having visions of passionless driverless cars in massive traffic jams while people caper across the road at randomly selected intervals…. doom for an industry?