The thing is, there are a lot of stationary objects alongside/near major highways (signs, bridge supports, barriers, etc.). The radar systems are not 100% accu

The thing is, there are a lot of stationary objects alongside/near major highways (signs, bridge supports, barriers, etc.). The radar systems are not 100% accurate about whether a particular stationary object is in the lane. In nearly all cases, stationary objects are not in your lane (if they were, the previous driver in the lane would have hit them). Thus the radars are tuned to detect non-stationary objects, as those are slowing cars, merging cars, etc. all of which are commonly in one's lane, and which require action from the Autopilot.