Opinion: level 5 autonomy would be cool, but it's not where most of the value of self-driving cars is. Most of the value in being able to travel by auto without attention is in trips longer than 15 minutes. Commutes, tourism, vacations. Shipping. Most of which is certainly highway driving. If it's possible to automate highway driving under most conditions (and safely transition either to a stop or human-piloting when…
Of course, I live in a city, where parking is a major pain. But the other things still hold. It it far more efficient of resources to have cars be used most fo the day, rather than sitting idle.