Chicken-and-egg. It's expensive to add a bunch of stuff to the road for computer cars to read, and if there are no computer cars to read them, what's the point?
Computer cars will lower the bar on what's valuable to put into the road. I can see the point in 30 years where computer driven cars are even simpler than today, because it made so much sense to add the automatic road markers, which made automating cars easier, which make all cars automatic, which led to roads being updated only electronically, which is now a simpler problem than today (driving on roads with only other computer-driven cars actively broadcasting beacons of their location and position, and road markers/signs/lights being trivial for computers to read).
Computer cars will lower the bar on what's valuable to put into the road. I can see the point in 30 years where computer driven cars are even simpler than today, because it made so much sense to add the automatic road markers, which made automating cars easier, which make all cars automatic, which led to roads being updated only electronically, which is now a simpler problem than today (driving on roads with only other computer-driven cars actively broadcasting beacons of their location and position, and road markers/signs/lights being trivial for computers to read).