> What happens next? A bus? Light rail? Uber/Lyft/taxi? A friend who has time to show up? Renting a car? What's our next move? (Lots of destinations don't have much for local public transport.)
You're saying all this as if this exact scenario isn't solved in plenty of places across the world? You take the bus or tram or metro or cycle or just walk if it's close enough. If the city is actually built with public transport in mind, not just a single bus line that runs every 2 hours bolted on as an afterthought, those options can be easier and faster than finding a parking spot, unless you feel entitled to park your vehicle anywhere you please to the detriment of everyone who isn't you.
Where I live in the Netherlands it's faster to bike most places than driving, because we don't solely cater to drivers and don't devote half the city to letting people store their cars. Even up North in the villages you can still get around by bike, since cycling lanes are dead cheap to build and maintain and can go down in the middle of a swamp if you needed to.
> When I drive myself to Somewhere, I've still got my car to use after I get there.
Sure, and when I cycle to Somewhere, I've still got my bike. Same logic, except I can lock it to a post and forget about it rather than needing to find a dedicated slab of real estate specifically reserved for my vehicle's existence. And if I took the train, I can rent a bike when I get there, which is a thing that exists in basically every city that actually invested in making it work.
> I can go anywhere I want to go, at any time I choose
That only holds true because decades of car-centric design have made it so. In the Netherlands you couldn't just go anywhere you wanted by car, because there are plenty of streets and whole areas where cars flat out aren't allowed, because we actually prioritize the people who have to live with those infrastructural choices over random passersby who don't want to be "inconvenienced" by having to walk 5 minutes or share the road with someone who isn't also in a car.
If the US bothered to build out the infrastructure, you could go anywhere you wanted to go via public transport as well.
What happens in your scenario if you can't find parking anywhere near your destination and the only option is lugging your bags along roads that weren't built for pedestrians? I know I've been in similar situations in the past where I had to drive around for fucking ages trying to find a single spot, I definitely would've preferred walking than that whole circus.
> I might have been better-rested if I took the hypothetical train, but getting dropped off at a train station isn't a very complete solution.
Right, in a country that gutted its public transit and zoned everything to be car-dependent, a train station by itself isn't a complete solution. That's a policy failure, not an argument against trains.
> If the US bothered to build out the infrastructure, you could go anywhere you wanted to go via public transport as well.
Public transit != mass transit. There's no reason that self-driving vehicle fleets can't be municipally subsidized and provide a dramatically better private experience than any mass transit anywhere in the world, and we already have the infrastructure for it.
How many private vehicles do you need to provide mass transit away from a mass event such as a stadium, or a concert?