The debate is whether we wait for society to change or we change the technology. If cars didn’t pollute the existential threat from cars is removed. That problem is pure engineering and tractable, while social change is unsure and difficult thing to accomplish.
This isn’t the end of car related issues. But we can and should address the engineering and technology addressable things, and concurrently with the social change. As you say it’s existential. There are a lot of other issues about car culture - the extensive use of land for car infrastructure for instance, that are important, but not existential. I even think making biking safer is important, but it’s absolutely not existential. A less car dependent culture is neither necessary nor sufficient to address the issues of tire microplastic, co2 release, etc, as we still have the use of cars as they exist pervasively for other reasons than going to the store.
My point though is that people like driving so they will drive even if it kills everyone. That’s abundantly clear. People move out of urban cores into suburbs partly because of the car culture is more to their preference. That’s not a new phenomenon and it’s not restricted to the US. Many friends in UK, Holland, Germany, etc, moved out of the cities for a more suburban car centric life. So, if you can’t easily change the behavior or preference (which I never see happening in a democracy), then why not address the ways in which cars destroy the earth? The logic doesn’t make sense to you because you posed a false dichotomy. The options aren’t “destroy the earth with cars or save the earth without cars,” because cars don’t necessarily have to destroy the earth.
As an exercise of the imagination, imagine hydroelectric charged hovering quadracopter electric vehicles. They no longer produce microplastics or co2. Their batteries are 100% recyclable. What specifically would the issue be then? Is it absurd to imagine such a thing? Given current technology, it’s absolutely NOT absurd. Given future technology it’s fully achievable. Instead of flying vehicles, maybe just not touching the ground is enough? Etc. This may not be how we solve the issues, but it’s a lot more plausible in my mind than convincing everyone to pack into an urban core and stop driving to Costco.