For example look at the 'getting here' page for a random national park, like Zion. It only lists directions for private cars. Presumably if there was any other way of getting there then someone like the National Parks would make it extremely clear how to do that. Are there train stations near Zion? Would you literally take an Uber all the way there from a major city? It would be hundreds of dollars wouldn't it?

If you got an invite to join your friends hiking for a few days in Zion next week, how would you get there?

I think you're going to reply 'well obviously you can't quite do everything and I wouldn't be able to do a climb far from a central visitor centre or join those friends' and bingo, I think the bar for what you can do outdoors without a car to get you there is pretty sad and you'll be missing out rather than living some high life of car freedom.

My car's paid for, sits out of the way in my garage and costs me a week or so's wages a year in maintenance, fuel and insurance. It's an effective tool to get out there in the world and do things with basically zero negative impact on my life.