Google's cars use Bayesian reasoning. — How does that change anything? What's an alternative to "bayesian reasoning?"
Google can probably tap into the government data for new stop sign installments anyway — such a thing (an accurate government database of new stop signs) does not exist.
the prior probability of a stop signing being there — scenario: a construction worker with a rotating STOP/SLOW hand sign during road work. Or, manual traffic overrides with police standing in the road with hands up or hands waving to manually control traffic.
the car can look at cars in front — assumes said cars exist and the motion of forwardness is more important than any potential cross traffic being stopped for.
