NHRA requires them in the upper classes TF,FC,TAD,AFC, I'm not sure what's required in the other classes. The emergency crews need to have their training, and hardware ready, for them to fully function properly when needed.
The ones I have seen need a air pump to be used by the first responders. They cut the chinstrap and pump the air bladder up to lift the helmet off. I guess that's better in some cases than just yanking it off.
Rouse