I'm not sure about this... Do you have sources on that ?
I'm pretty sure that on contrary, autonomous car constructors are actually testing their cars in the worst possible conditions even some that are unlikely to ever happen to anyone. At least it's what Google is telling about their test process.
the real shocking truth is none of these systems is capable of driving when even skilled drivers might need the assistance. think about it this way, car safety systems are designed to insure recovery of safe driving during some of the worst conditions yet self driving systems cannot handle most of these poor conditions as they cannot accurately see and assess the situation.