Yes! This annoys me to. There were tens of millions of people living in the UK and we didn't all think and act the same.
For what it's worth, I was very close in age to Diana. I went to a very academic school where most girls stayed on for A levels and the vast majority of us went on to university, polytechnic or some form of professional training. This was very, very unusual at the time (it was decades before I fully grasped how incredibly lucky we'd been), and certainly didn't apply to the boarding school Diana was sent to.
I then went to university and met a mature student six years older than me. We got married while I was still a student, the year after Diana and Charles got married. (Still married now.) Two female students from my course got married that same summer. I'm not in touch with them now, so no idea whether those marriages lasted. One of them already had a child, which was very unusual at the time. A factor in these early marriages was parental disapproval of couples living together (it certainly was for us, my parents were aghast). However, my husband and I didn't have children for many years after we married as we were both working in professional jobs and concentrating on getting our own house.
Lots and lots of my colleagues (accountants) got married in their 20s, but not many had children immediately. By about 1990 when we were in our late 20s most of the girls from my year at school were married with children. These first marriages didn't always last. (We had a reunion a few years ago, very interesting.) The vast majority of them continued with their careers in some form or other. This is where us plebs had the advantage over Diana. We had education and we had work.
If Charles had found someone like Catherine M, she would be Queen now. Diana was not psychologically suitable for the role her family and his had assigned her. It's a great shame that nobody saw this.