Why does being able to specify the route matter? Because Google Maps (and other earlier and still existing navigation programs) are so often wrong, or choose the efficiency of taking the largest road rather than smaller ones that are actually more efficient (or less dangerous, or less subject to flooding in a storm period...) I have now quit using I-35, for instance, except on early Sunday mornings. I've been caught in too many traffic jams (one, lasting two hours, cost me an extra trip to a post office to get my passport renewed.) So I go into Austin via a smaller highway, happily putting up with some stoplights in some towns along the way for less stress (sitting in a traffic jam is stressful to me, and so is the crazy traffic on the interstate that causes the accidents that cause the jams.)
And of course, the operator needs to be able to tell the vehicle where the operator wants to go. In my case, for both fuel and time economy, many trips to the city involve multiple destinations, in and out of grocery store and other store parking lots, to a friend's house, etc., and if they're familiar ones I know short-cuts and back ways to avoid various hazards. How would entry to downtown garages be handled, where the driver must take a ticket from a machine to gain entry, and hand in one (or two--in case of one I use every week) tickets to a machine to get out? This means that in all weather conditions, in bright sunlight and at night, I need to be able to communicate to the car where to go, including (for mall parking lots) choosing a parking space within my walking capacity (which isn't impaired enough to qualify for handicapped parking, but is sometimes impaired enough to make the last row out too far, especially if it's a slope and I'll be walking back uphill with purchases.) How is that done? Judging by the way high-tech companies ignore the visually impaired customer (my current desktop is a prime example, with tiny, barely incised black on black symbols for things you plug into the front of it--can't feel them, can't see them without a magnifying glass and strong angled light), I foresee that the very people an autonomous vehicle might find most useful could end up being useless because no one considered them in designing the control interface.