Stationary objects are less likely to be recognized than moving ones: https://www.wired.com/story/tesla-autopilot-why-crash-radar/
Even WAAS GPS [1] (used by autopilots for airplanes) is specified to be accurate only up to 25 ft, although the measured accuracy is usually around 3 ft.
[1] https://en.wikipedia.org/wiki/Wide_Area_Augmentation_System