Feels like this is the curse of modern US politics. I'm convinced the majority of people that "want high speed rail in CA" don't live in CA. Further away they live, the stronger they will argue for why we should have it.
1) I wish we had better rail transit in the bay area and to the areas surrounding the bay
2) I have to own a car to get to places in Northern California
These don't seem like remotely contradictory positions.
Which, to be fair, people online have a habit of just arguing past each other.
And in most countries we wouldn't call multiple cities of 100k+ population 'nothing'.
HSR is the spine of the transportation network, that local and regional traffic docks to making a greater whole. It increases the reach and power of public transport as a whole.
For HSR to be successful, you need people using the in-between station for regional trips, not just end to end airplane like trips.
I guess there are some very passionate rail fan liberals in the Eastern united states that hope for true HSR on the East coast that really root for HSR.
But then again I have heard plenty of Californians passionately denounce/advocate for the project.
So I don't think your observation holds.
The VAST majority of people I would see have conversations about this seem to want others to take transit so that traffic is better for them in their car.
I lived in the UK for 2 years without a car and it ultimately did not negatively impact me (other than needing to memorize local bus routes). I lived in towns as small as 10000 people (Newtown, Wales) and they had both a connected rail system and a couple of bus routes serving the town and connecting it to other towns.
Buses absolutely can work in even quiet rural locations, they just need to be properly funded and prioritized. They also need to be subsidized. The American notion that public transit needs to either run net zero or turn a profit is backwards and fundamentally stopping it from working well.
The underlying issue remains that it is seen as a poor person option. As soon as people can afford a car, they get one.
Back when I didn't have a car, my future wife and I saw a comedian that literally had a joke about being above the poverty line of "do you take the bus?"
And the reason it seen as 'for poor' people is because you only use it when you can't get a car.
So the underlying issue is the overall quality of the service (frequency, reliability, comfort and so on).
Again, I lived for over a decade with a tech job and no car. In Atlanta. It is easily doable. Especially for younger people that don't have a family. When I got married and we started having kids, I never had "my" car. Stayed on transit and cycling to get to work.
It is frustrating, because I would be surrounded by progressive people at work that would go on about why transit doesn't work. But... it did. Just fine. You just can't also have a 4k square foot house at the same time. (I feel like I'm exaggerating, but that is literally the size of average home in some areas just around Seattle. My shared living in Atlanta was almost 1000 square feet. I remember dreaming of a 650 square foot "luxury apartment" someday.)
Look it might be easily doable for you, but the data shows pretty clearly that if one thing is easier and faster then another, most people, not all people will pick what is easier and faster. There are always 10-20% of people who will just prefer one thing, no matter what. See people who ride bikes in horrible dangerous conditions threw traffic. You might be willing to, but most people are not.
But what you need is a system with enough quality that enough people use it so they can demand continued increases in quality.
Even in places like Tokyo, you will find that the wealthy neighborhoods have cars. The catch is in Tokyo, this is enforced by law. If you can't show that you have a legal parking spot, you aren't allowed to register a car. That is a very steep hurdle that makes the vehicle far more than just 10x. And is a large part of why even the largely confusing mess of major transit offerings that will require different tickets works, there.
In spite of that, commute times in Tokyo are, on average, still HIGHER than SF and NYC commute times. My commute time even on public transit in Atlanta was better than the average commute in Tokyo. I don't know how you want to start quantifying "worse" or "better." Are they "workable?" Yes. Absolutely. Will people use if they can afford to get and operate a car? No.