Drunk Drivers create havoc for self driving vehicles.

U.S.P.S semi-truck driver dies on California freeway

https://www.postaltimes.com/postalnews/usps-semi-driver-killed-in-oc-22-freeway-crash/

U.S.P.S using self driving trucks
https://www.postaltimes.com/postalnews/this-autonomous-truck-test-was-boring-and-thats-what-the-usps-wanted/

This article sounds like this program just started. I've been told by U.S.P.S truck drivers they've been running a pilot program driving them since late 2017.