Can anybody who understand the market give me a reason as to why aren't smart roads built simultaneously to these driverless cars? I mean, why focus on making a

Can anybody who understand the market give me a reason as to why aren't smart roads built simultaneously to these driverless cars? I mean, why focus on making a car able to 'see' rather than being able to communicate with it's infrastructure? The reasons I thought of: 1. As mentioned - building/upgrading infrastructure is probably much more expensive and logistically elaborate. 2. Market penetration - current batch of driverless cars can drive on existing infrastructure - no need to wait. 3. If smart cars won't be usable dumb roads it will also be hard to sell 4. Smart, durable, cost-effective infrastructure hasn't been solved.