They do have two. On road courses especially long ones more are needed. Many local/track teams are quite good.
I commented quite a bit in one of my regular columns in the Garage Blog on safety issues and not just on IC.
F1, NASCAR, ALMS, IC and Grand Am plus others had better take a good look at their procedures.
For some reason fires seem to be occurring more frequently and if anything magnesium gets going it is extremely difficult to extinguish.