Except generally pre-owned is short for certified pre-owned like it is here, which means you get a much better warranty than buying on the used market.
I remember a time when it was "certified used".
Most dealership websites in the US list cars as New, Pre-Owned or Certified Pre-Owned, meaning Certified is distinct from Pre-Owned.
But that nuance wouldn't allow them to get outraged about something trivial.
You're paying for that warranty though. If you really want one, you can buy one yourself from one of several competing aftermarket warranty companies.
Used car dealers suck, in every way. They add zero value other than having a selection of cars in one place, and possibly a selection of lenders for financing if you need that. They also know every trick in the book to get you to pay more for the car than it is really worth.
Best way if you have a little time to do research and watch the local market is to buy a car from a private seller.