All of the self driving systems I have intimate knowledge of have some level of "persistent memory". It dramatically improves performance in a lot of common sit

All of the self driving systems I have intimate knowledge of have some level of "persistent memory". It dramatically improves performance in a lot of common situations, e.g. you're coming up to an intersection and your view of stationary cross traffic is occluded by a bus/truck. You enter the intersection and now the planner has to decide whether that vehicle is on an intersection path with the SDC. You only have a few frames of information without persistence and the velocity error might still be large. Thus the safety system has to slam on the breaks to avoid a collision that will never actually happen, potentially causing a real accident if the car behind is following too closely.