I have a youtube video from 1995 with a sprint car hitting the turn four tires and flipping (1:05), a stockcar going into the Paragon pond (1:38), and a stock car gets pushed into the turn four tires and flips (2:30). So it happens, or did when I went to Paragon at least, kinda often. But I'd rather hit those tires at 60-80 mph than the attenuator in turn 4 at IMS at 200 mph.

https://www.youtube.com/watch?v=KAHs1arQkDk

There was a street stock that hit it about a million years ago and turned over. Beleive it or not, it was a full sized caddy or lincoln.