If a six-foot gate is not enough, a seven-footer could be installed; but then someone would inevitably say that nothing less than a eight-foot, triple-reinforced gate will be adequate. Where does it end?
There are plenty of things that could be done to increase safety; but all of them come at a price, monetary or otherwise. Personally, I wouldn't want to live in a 100% risk-free world, assuming that such a thing is possible.
"dominated by big-money commuter and executive jets" ... I know exactly the kind of place you mean: sterile, anonymous places, populated exclusively by bored non-flyers and professional pilots wearing silly white polyester shirts with four gold bars on the shoulders. If an old biplane ever chanced to fly in, it would be uncermoniously warned off the premises (can't have those wretched anachronisms dripping their dirty oil on our spotless apron!).