Look at this piece I found just now..
http://espn.go.com/racing/nascar/cup/story/_/id/9329545/jeff-gordon-renews-call-barriers-everywhere
Exerpts from the article..
"We're not the only thing that runs on a given facility," France said of NASCAR. "That's No. 1. If it's a motorcycle event, Moto GP, something else, which is contemplated being run at different facilities, that has to be considered.
"From NASCAR's standpoint, we look at that very carefully. We were all over the California circumstance. When we need to put additional SAFER barriers anywhere, we will do it. There's nothing that prevents us other than that we look at this, we think we have them in all the right places, and if we don't, we'll make an improvement, like anything else."
-Brian France
Gordon said there's only one reason there aren't barriers everywhere.
"Cost," he said. "There's only one reason. Cost. That's it."
I had it right. Its all about the money, as usual with NASCAR.