[Kputz]

Coy, you've evidently not attended a school, rather a real school. Cars are generally kept far apart, and oddly enough speed is rarely an issue, nor is it emphasized all that much. They actually make an attempt to teach you to drive and the number of offs at a professional school is remarkably small. They actually teach you that fast in road racing is corner fast, not horsepower fast, and it that takes more brains than motor to actually BE fast. I've been to my share of open events and the above description is hardly the norm.
About the arm restraint, it shows you're beginning to get it. Now then, if the open event REQUIRED either arm restraints OR window net, we'd be getting to some common ground here.
My point remains, the man asked about liability. He has a far greater exposer to liability risk at an open event than any other kind of event involving cars that I can think of. That he cared enough to ask is proof that he is a thinker, and deserved an answer. He got it.