People are making this seem like a car tech, or self preparation problem, it isn't. This collision occurred at RTTH7 autocross. Here is a video of the event:
Parts of that make me CRINGE. This autocross should have never happened, the course wasn't safe, and the venue wasn't adequate for the type of course. This should have never been run to begin with, and it was only a matter of time until something of this nature occurred.
To give the entire story since everyone is beating around the bush here, the event promoter is Bill Howell. Bill started a thread on Pro Touring about how he knew that these cars, and courses were unsafe, and that we might need to require more rules, and better safety equipment. He then later deleted the thread, I'm assuming so that when something like this happened the insurance carrier wouldn't see that he had concerns, and he could limit his liability.
I think this falls into the 6P's category. Proper Planning Prevents Piss Poor Performance. In this case someone with experience, such as a SCCA steward, could have drastically changed this course, or even ruled the venue inadequate and prevented this entire thing.
To be fair, Bill did promote the RTTC2 event that I went to, and the courses were exceptionally well designed. The autocross and road course both were safe, fun, and challenging.