Forgive my ignorance, but isn't this not supposed to happen with LIDAR equipped cars?

My understanding is that a LIDAR provides a completely accurate 3D map of the surrounding area around a self driving car. This is in contrast to Tesla's image recognition approach which makes a 3D map from 2D images. So is seems like a pretty giant bug if a self driving car ever crashes into another object with LIDAR, since it should always know the location of external objects.

Please correct me if I am wrong!