Self driving cars aren't going to be terribly good at measuring road feel and that moment when you feel grip suddenly let go and make the correction to stay on the road.
I wish I could see your face when I tell you that the technology to handle those situations has been mandatory in all cars (though not trucks) sold in the US since 2010. It's commonly known as ESP (electronic stability program) and there are a number of ways to actually effect changes in vehicle yaw once it is detected via accelerometer, like decelerating a slipping wheel (with the brakes) or accelerating an opposing wheel (e.g. with an electronic differential and the engine.) Slip can be detected as well (by the use of a second accelerometer) and one common response to slip is to engage traction control, which of course can induce yaw... which is then handled by the ESP.
This stuff began to become ubiquitous in high-end cars around 2000, but it was first brought to the street by Mitsubishi for the Lancer Evo IV and also used on the Galant VR4 and 3000GT VR4, under the name AYC. Even though it was the pioneer, it used the more complex and expensive electronic diff method, which is better than braking because it doesn't slow the vehicle.
All it would take to mess up AI racing is an oil slick or an animal or person or a tree falling or a part falling off another car or any number of other things for the AI to become overwhelmed.
The AI will deal with the oil slick better than a human driving a car without traction control and ESP, because it will effectively implement traction control and ESP. The vehicles already watch for obstacles. It's not that they won't ever make mistakes in these situations, but humans often do as well, so that's not a differentiating factor.