Venturing a guess -- there's either some X% accuracy standard required by the government for who-knows-what reason, or it's for red light cameras and ticketing systems.
"Ironically, the biggest concern with red-light camera systems is that they are so precise. They measure a driver’s speed and exact location within a fraction of a second — but do not leave any wiggle room for the errors of traffic signals such as inconsistent yellow light times"[0]
If there's not an accuracy threshold for safety reasons, there's gotta be one when traffic ticketing revenue is on the line (also I guess determining fault at accidents, vehicular manslaughter cases, etc.)
"Ironically, the biggest concern with red-light camera systems is that they are so precise. They measure a driver’s speed and exact location within a fraction of a second — but do not leave any wiggle room for the errors of traffic signals such as inconsistent yellow light times"[0]
If there's not an accuracy threshold for safety reasons, there's gotta be one when traffic ticketing revenue is on the line (also I guess determining fault at accidents, vehicular manslaughter cases, etc.)
[0] https://www.mercurynews.com/2014/06/06/red-light-cameras-how...