Banning the chemicals that were eating a hole in the ozone layer worked pretty well, as a quick relevant example, and that ban was global.

The ban would not retroactively remove cars, it would ban the future sale of gas cars by a certain date. This would be like Reagan saying "In 10 years we will be drug free, and drugs will be illegal then.", then providing a pathway for people who are struggling with addiction (in the car case I'm not sure how much 'treatment' would be necessary, electric cars are getting cheaper and car companies are making more electric ones anyway).

Obviously a person addicted to opiates has little choice in their addiction, it isn't as if they make a clear headed decision every time they use, and there isn't an alternative that is the same but legal. Like the ozone eating chemicals, on the other hand, the type of car you buy and drive is absolutely a choice, and for the vast majority of miles traveled, you do not need one type of car over another. For the specific scenarios you do, gas cars sold before the target year and ones sold in other states are still available.

The argument you made is far more accurate if all cars were banned under the law, but that simply isn't the case. It was banning the future sale of them in the state. The eventual death of the gasoline automobile is both necessary and inevitable (to personal electric vehicles, or some other transportation), and the timeline is all we are arguing over here. California wanted to speed the timeline up to help the climate, the extinction speed runners felt like that would hurt Exxon mobile, so they blocked it.