Taking away roads doesn’t make cars any less convenient. It just means that fewer people will travel to that area.

Mission success I guess?

Well, it actually does.

The convenience of a car is determined by how likely you choose a car over other means when you need to get somewhere. If there's less roads, you're less likely to choose car, thus the lowering the convenience factor. If there's no roads at all, owning a car is meaningless since you can't drive anywhere, and its convenience is pretty much zero.

So you've still made the whole experience less convenient in absolute terms but made another option more convenient relatively. That is not a success. It's like dumping a pile of venomous snakes in the upstairs bathtub so now I have to go downstairs, thus now the downstairs bathtub is more convenient.

Roads make driving more convenient at the expense of other transportation methods; being able to walk to the store is more convenient that driving there. You can't do it though if there's this huge highway in the way and your city is so low density that the store is miles away.

If this argument doesn't convince you, think also that driving may be convenient, but I find more convenient if we lived in a planet that's not a literal oven

I wouldn't find walking to a store more convenient than driving unless the walk to the store was less than the walk from the parking lot at a store I'd drive to.

even if it takes less time? for driving you have to get to the car, drive, deal with traffic, park, and so on

Driving for 10 minutes is generally more appealing to me than 5 minutes of walking carrying bags, but it depends on the situation. I bike a few minutes to a nearby McDondalds sometimes but then often drive that same distance.

I'm not arguing about that and not trying to call it a success. I'm just stating that taking away roads does in fact make cars less convenient.

Sure, if there are no roads at all.

But if SF makes a street pedestrian only, it just means that area is more inconvenient. And it might not even mean that, since the inconvenience will reduce demand so those who still drive there may have about the same level of convenience.

Replacing roads with public transit does not mean that fewer people will travel there. It often means more, as proven in hundreds of cities around the world.