I agree (and often use the same example of cars). I believe the reason is simple and sad - UI is meant to sell your product (or more likely these days, service). UI and UX panders to new users because that's who they have to impress; after purchase/subscribe decision is made, their feedback rarely matters (and there are plenty of ways to make them stick around, including exploiting sunk cost and network effects). Add to that the fact that regular users accept what they're given, because they have little experience to know things could be better, and you have a perfect recipe for UIs promoting sellability over user productivity.