Two things here. One, NASCAR is always wary of adding new tech to the cars for cost reasons, and for the possibility of someone exploiting that technology for their own advantage, such as using it to make an anti-lock brake system. Second, I think NASCAR likes to keep things that require skill and makes people more responsible for themselves instead of having it done for them. I think that's why we still have five lugnuts, dump cans, and a H pattern transmission instead of paddle shift. If the drivers weren't trying to push the cushion they already get from NASCAR on the pit road speed down to the last tenth of a mile per hour, they wouldn't get caught speeding.