Stop making bad human drivers an excuse for these machines to also be bad drivers. We're striving to do better, that's the whole point.
What if the bus driver took a break and forgot to turn off the sign? What if it had been 10 minutes and the driver was obviously dealing with some kind of behavioral problem?
A human is not going to put their life on hold forever just for a flashing light. Part of being a smart AI is figuring out when the rules have broken down just a bit and you have to adapt.