As accidents go, it wasn’t much of a fender bender.A Santa Clara Valley Transportation Valley bus was moving forward at 15 mph.In the adjacent right lane, a Lexus SUV was getting ready to turn right but sandbags around a storm drain appeared to be an obstacle so the car hugged the left side of its lane and struck the right front of the bus.This isn’t the type of accident that would make national news. Unless, of course, the Lexus was a self-driving car being tested by Google.If you aren’t a major critic of driverless cars, such an incident probably doesn’t worry you much.Google said its computers reviewed the accident. That review led engineers to modify the software controlling the car to understand buses may not be as inclined to yield as other vehicles.No kidding, Sherlock.The fact engineers quickly adjusted software may make you comfortable with the entire notion of self-driving cars given the fact they are a work in progress.But here’s the rub.