I think it's quite different to look at a random select list of things many youths experience and say "I didn't do those things either" ,(nor did I, for the most part), but most of us will be living life wildly differently now to how we did at 13, 20, 30 etc (depending on age now). Life moves on over the years and we (general we) move with it. We experience different things, have different responsibilities etc.
Sue's life, at 45, is pretty much identical to her life at 20 (I won't say 13, as clearly her parents helped a lot when Chris was tiny). At 20, she had a few kids, was spending her days changing nappies and cleaning up after young kids, doing school runs etc. She's doing exactly the same 25 years later, just with a hell of a lot more kids and more money. She's literally never had a life away from the hone, away from Noel and the kids. She's never experienced going out to work, meeting new people (except other mums at the school gates - although she's usually running late so probably doesn't see much of them either!). At 45, her life has never been her own. Most people have a period of "finding themselves", learning to fend for themselves, before they start a family. Most people then start gaining that independent life back when their kids become teens and older and start branching out on their own life adventures. Unlike most adults, Sue has never had any of that and never will do. Even if Heidie is truly the last, Sue will be in her 60s by the time she turns 18 and will probably have 20+ grandkids by then. Her life has literally revolved around babies. Most people get that stage of their lives over with in less than 10 years, before repeating it slightly with more enjoyment 20-30 years later with grandchildren.