Because it will never be needed.<p>The steps go like this:<p>Driverless car in a dedicated lane. That will be first since it&#x27;s much easier to build than local driving or mixed long distance. It also covers the most important need (i.e. much less economic reason to make one for local use).<p>Lots more people see how great that is, so more cars (and trucks) will be rapidly added. That lane will reach capacity, so more lanes will be added.<p>Within 5 to 10 years driverless long distance will be the norm, and long distance driver cars will be rare. (All the cars will be have mixed modes, with the driver taking over for local streets.)<p>Every new car will advertise that it includes diverless mode as a feature.<p>All this will happen so fast there won&#x27;t be time to perfect a mixed use car.<p>By the time they do perfect a local driverless car virtually all cars on the market will already have long-distance driverless mode. And the ones that don&#x27;t will probably get retrofit kits.<p>So at no point will mixed long distance ever be a thing - by the time the technology is able to do that, there won&#x27;t be any cars that need it.