Gee, I dunno, maybe because an out of control, unconscious driver could drive into the grandstands and kill spectators?
Have you missed those incidents where cars drive into the crowd? Or the WOO cars the flip over the guardrails and into the parking lots?
Then you get those spectators who will complain about everything complaining that the cars are too far away because of the extra distance you'd need to keep the speckies and the racers safe.
NHRA owns a few tracks, yes, but there are tracks out there that are independently owned (so to speak) with budgets and city and local regulations etc to deal with. I think that each track owner, manager, safety safari, etc does the best job possible given each situation in preparation for an event. I don't think there is willful negligence.
If each track had to be a certain length, width, color, temperature, altitude, you'd lose tracks.
If the name of the game is making everything universal so every race track is the same, why don't we just run at one track 23 times a year?
Racing is dangerous, and despite the best intentions and efforts of everybody involved, sh!t does happen. It's painful, it's regrettable, it's emotionally draining. We learn from them but for every safety precaution out there, there is a still a 'freak' or in my opinion, 'God factor'.
If we want to eliminate the human injury/pain factor, we would have to eliminate the humans.