All transportation is about efficiency.  Efficiency is a product of competence.  All users of transportation want safety.  Safety is also a product of competence.  The state, in thrall to the power of the Petro-Car-tels, gulls the public into believing that safety can be achieved by allowing incompetent people to drive and controlling them with regulation.  We are gulled into believing that as long as drivers obey the law they are competent.  All that is accomplished is the destruction of efficiency.  So all that we try in the way of infrastructure to gain either efficiency or safety will fail as long as incompetent people drive.  You can engineer stupidly.  The northbound Delta to westbound Belt Line on ramp is a prime example as are left turn signals that don't last long enough to handle even the competent flow of traffic.  However, you can't engineer for stupidity.