"Just as a somewhat tongue in cheek response: I have a colleague who doesn't drive, we find ourselves being questioned on this really frequently. Similarly with not eating meat. It seems that because it's not "usual", it's a topic of much interest to other people. On occasion, we do wonder to ourselves whether those people would get annoyed if they were frequently asked "why do you drive?" or "why do you eat meat?" :D

Funnily enough both my adult children do not drive, could be from living in cities that had adequate train and bus facilities when they were younger. The fraught area of vegetarianism is another matter though, I compromise by eating more vegetables 80% and less fish/chicken 20%.
Thinking about travelling to megalithic places without 4 wheels though does probably narrow the experience unless you are a back packer.