Full disclosure, I have an older Tesla with only Auto Pilot (AP). I agree with the sentiment that autonomous vehicles won’t lead to some congestion free utopia. I do however, think they would improve conditions for the people in them, and quite possibly diminish conditions for people still driving.
When driving with AP, I’ve found myself many times pacing behind a car going slower than I set my cruise for. It’s much less mentally taxing and easier driving like that, lending to an overall better experience. That’s similar to how I see autonomous vehicles being implemented. They might add to congestion and increase drive times, but the “driver” won’t care. Unfortunately for those not in autonomous vehicles, this also increases their drive times.