The OP question "people who can actually afford cars, and are getting older, or are old why do you not have a car" doesn't really make much sense to me. I don't need a reason to not have a car - I need a reason to have one.
I am in my mid-50's so I am "getting older", and I do have a car now so I can "actually afford" one. Not long ago I didn't have a car, for a short period I did have one that barely worked and no reason to repair it - I just didn't care. No reason to buy one, or to fix one. For the normal uses- commuting, shopping, errands, recreation - it just wasn't needed, and I could rent one for special trips or hauling something.
Since then I've had some reasons to own a car (which I won't go into), so now I have one. It doesn't make sense to ask "why not" without reference to some reason why I should.