Forgive me, I'm not a pilot, but I have certainly played a lot with aircraft in my time as a MAOT. Out FACing one day on SPTA, and had a lot of fun with a Tonka beating us up at VERY low level. On another day, an A10 doing the same thing (difference was, I knew the Tonka was coming!). On another day, a Puma beat us up at no more than 15ft. Excellent fun, and I can see some training value for the aircrew with such low level flying in a military environment.
I can contrast this with those idiots "train surfing" who get surprised when a bridge spoils their whole afternoon. Or those that think the 25KV overhead lines are handrails as they mount the train roof.
Not the same to me, but I guess there are limits, which like all rules, get broken from time to time.