Fuckcars is made up of people with little life experience who think they have all the answers, and people who fetishize city living and think it's normal or healthy for humans to live at a density like NYC (and fuck you if you disagree). They're oversimplifying to the point of meaninglessness, and handwaving away the problems.
What's far less dense with better public transit than NYC? The most popular example of no-car city design I see is Amsterdam, which is 1/2 the density of NYC, but still 15x the density of where I'm from (not even close to a rural area). I think robust public transit at 1/15th the density of Amsterdam and 1/30th the density of NYC is a pipe dream.
In these lower density places, maybe you luck out and you're walking or biking distance to work. If you change jobs do you have to move instead of hopping in the car and commuting a bit further? In circumstances like these, transit can't possibly serve every origin and destination efficiently, and personal vehicles can offer efficient point to point.