Circuit "Safety Provisions" can have one of two objectives - Safety of the competitors or Safety of non-competitors (spectators and occasionally marshalls or pit personnel). Generally the two run hand in hand, but I am sure there are some circumstances where reducing one risk means increasing the other. This is the reason that people nowadays carry out formal risk assesments.
The "elf 'n safety" decisions that infuriate us are generally taken by people who don't fully understand the formal "Risk Assessment" process and apply risk mitigation measures indiscriminately. To try and avoid this issue the Construction safety law includes the term "Where reasonably practicable" but even then, some people, and organisations, are overly conservative.
Believe me Track Inspectors get it wrong often. Often the dynamics of racing is NOT taken into acount. Nor is commonsense for flag locations, from a vision perspective and sometimes the flag point is vulnerable to be hit.
'Temporary' circuits are worse too as the circuit has to go around eg a tree which makes the wall stick out to be hit or most flaggies are more vulnerable as they waving through a gap in the catch fencing behind a big concrete block they is NOT secured in place, just relying on its own weight. They can and do move quite a way when hit.
Worse what is great for bikes is not so good for cars, air fencing. I have seen a FF bury itself under it and the driver could not get out. That was ok as the car did not catch fire. Kerbs that may be ok for cars can launch a bike big time. Though many kerbs can do that too a car, some are as high as 500mm. Worse at one satge many were corrougated on top. The idea is to keep the cars down, ok it does unless you are avoiding a spinning car,, or just having your own private accident. I damaged a fuel tank on one of those and many damaged exhausts. But hit them wrong [with or without corrougations] and they will launch you in the air and possibly into a wall.
Smooth walls are safer to hit at less than 45 deg angle as you bounce off, tyres or earth walls tear the car to bits as they GRAB. Sometimes better though for bikes. Head on tyres are the best, better than air fence except again for bikes.
Really a circuit that is safe for bikes can be lousy for cars, even open wheel or really low sports cars require different dynamics than a tintop or large sporty.
With a deal of work you can change the worst of it for bikes or for cars, a 2x4 meeting [and I wish there were more] will always be a severe compromise. But open wheelers and tintops are generally always on the same bill.