On Monday, a Tesla Model S slammed into the back of a stopped firetruck on the 405 freeway in Los Angeles County. The driver apparently told the fire department the car was in Autopilot mode at the time. The crash highlighted the shortcomings of the increasingly common semi-autonomous systems that let cars drive themselves in limited conditions. This surprisingly non-deadly debacle also raises a technical question: How is it possible that one of the most advanced driving systems on the planet doesn't see a freaking fire truck, dead ahead? Tesla didn't confirm the car was running Autopilot at the time of the crash, but its manual does warn that the system is ill-equipped to handle this exact sort of situation: "Traffic-Aware Cruise Control cannot detect all objects and may not brake/decelerate for stationary vehicles, especially in situations when you are driving over 50 mph (80 km/h) and a vehicle you are following moves out of your driving path and a stationary vehicle or object is in front of you instead."