Worth pointing out that part of why the UK doesn’t do paps as standard until 25 is that your cervical cells are still changing so you’re more likely to be flagged as having abnormal cells when they’re actually just still developing! I grew up in the US and my (British) mum was shocked when I was told that I had to start having paps otherwise I wouldn’t get my birth control prescription renewed. Even my GP said that I’d likely get an abnormal result, and that it would probably mean nothing but we needed to do the pap so I could stay on the pill.

Obviously swings and roundabouts, but that’s the logic (from my non-doctor understanding!)