It does make sense. See the 85th percentile speed: https://duckduckgo.com/?q=85th+percentile+speed https://duckduckgo.com/?q=85th+percentile+speed Setting the

It does make sense. See the 85th percentile speed: https://duckduckgo.com/?q=85th+percentile+speed https://duckduckgo.com/?q=85th+percentile+speed Setting the limit at the 85th percentile and having most drivers drive at it creates uniformity of speed, which is known to increase safety.