> Further, I expect the number of cars on the road to go way up because suddenly so many more people can use a car. For example, every one without a license. Kids, elderly, disabled.
And in areas with already bad traffic, it will only get worse. Much worse. You thought LA or SF pre-COVID were bad? Those will be the "good old days." And that's not just traffic, that's also hunting for parking everywhere you go (those cars have to be stored somewhere, after all).
A comprehensive public transportation system means people unable to drive can still get around. People act like self-driving cars are the solution when we already had a solution but (at least in America) proceeded to tear it apart as soon as we heard "cars are the future, get with the plan" and derided public transit as "welfare".
Fundamentally, we cannot "fix traffic", self-driving cars or no, because a 15-foot car holding 1-6 people cannot hope to compete with a 30-foot bus holding up to 30 passengers (on top of the driver), and that still doesn't hold a candle to a single train car (an 85-foot Bombardier MultiLevel railcar, for example, holds 132 people...and has a bathroom).
Compounding this is the American obsession with single-family housing and large minimum lot sizes: it is a fundamentally inefficient and unsustainable use of land. There is not enough space to build in this manner in the areas most in need of housing (which are, not so coincidentally, the areas where most of the jobs are), and it is this same inefficient use of land which makes public transportation difficult to run frequently enough that people stop using their cars for most trips.
When you build densely, you can run comprehensive public transportation that alleviates the need to have a car every time you need to go to work, the doctor, the grocery store, the park, etc. This also means people who cannot drive are afforded far more freedom than if they were to live in your average American suburb where sidewalks and pedestrian infrastructure more generally are an afterthought.
Far from a utopia, the future self-driving car advocates proclaim would be a nightmare. A nightmare where people are more isolated [0], more municipalities are struggling with debt [1], and even worse climate change [2]. This is not the future we should be excited for, it should be the one we are attempting to prevent at all costs.
Self-driving cars are fine (not having to deal with the TSA would be wonderful), but the way people think they will reshape society is nothing but a net-negative - we shot ourselves in the foot, but the proposed treatment is just putting on a band-aid and calling it a day. A high-tech band-aid, but a band-aid nonetheless.
[0]: https://citymonitor.ai/environment/citymetric-advent-22-snap...
[1]: https://www.strongtowns.org/the-growth-ponzi-scheme
[2]: https://www.nature.com/scitable/knowledge/library/the-charac...
Edit: Another thing to consider - if self-driving cars enable way more people to get around, this isn't good for the environment because only 40% of US electricity is from renewable sources [3] (20% of that being nuclear, which we desperately need more of but which many environmentalists have an existential panic over due to envisioning them all as impending Chernobyls). Burning gas might be bad for the planet, but electric cars don't have a perfect footprint, either. In isolation, replacing all gas vehicles with electric (minus stuff like trucks) would likely reduce emissions, but adding a massive increase in trips would be far worse than if we had comprehensive public transportation in more cities and towns.
[3]: https://www.eia.gov/tools/faqs/faq.php?id=427&t=3