Human fallibility is always one step ahead of the attempts to engineer it out, no pilot wakes up and says "today I am going to knock someone's tail off", a terrible mistake and an unenviable situation that the poor guys find themselves in. While there are many developments that provide real improvements in safety, the rate at which stupidity advances seem higher than what technology and procedure can keep up with and so we paste over the cracks with directives, when in fact the basic tenets of the industry often suffice.
An aircraft that has the right of way shall maintain its speed and heading, but nothing in these rules shall relieve the pilot from the responsibility of taking such action as will best avert a collision
We are so caught up in the concept of chains of events that single acts of incompetence seem impossible and we imagine into existence contributing factors where there are none, other than humans make mistakes. Double the size of aprons, double the number of rules, double onboard anti-collision systems, double ATC surveillance systems, of course, there will be improvements, but also you lull more people into a false sense of security. And of course, you never lose the infinitely beautiful quality of what it is to be human, perhaps very rarely but occasionally to be at the point of an act of terrible stupidity and to not see it coming!