I think you may be projecting your own expectations onto others. I'm one of those folks in a small town, with kids. And yes, it absolutely does add to the daily workload. It is also incredibly rewarding and has gotten more so as the kids get older. In my opinion, having kids is a very expensive exercise in delayed gratification. The first few years will be rough. But, there are the small moments along the way which just make all that effort so very worth it.

It’s so unusual to go to the pub after work and everyone my age leaves before sunset and the only ones sticking around are in their 20s.
Where I used to live, people would arrive at the pub at 8 because they were watching a friend’s afternoon gig, at the climbing gym, or catching up with other friends first.
Here, they’re up at 5 to get ready, then get the kids ready...

This sort of thing is down to personal preferences and shifting priorities. When I was younger, childless and single, I would have enjoyed the more social atmosphere. As I have gotten older, married and had kids, my priorities and wants have shifted. The idea of hanging out at a pub with strangers for hours, drinking my paycheck away has lost any appeal. It's not a matter of not being able to, I actually go to a climbing gym several times a week. But, I go to climb, not to socialize. Sure, I talk with others, but it's not my focus while I am there. It's just that I don't want that sort of lifestyle. I'd rather be at home, playing games with the family or engaging in my own hobbies. Let the young bucks have the pub, I have "better things" to do with my time. And, I suspect you're the other side of that coin, you likely see the time out socializing as the "better things". Far from being "miserable and broke", I'm actually really happy with my life and in a good place financially.

I feel like I don’t belong here simply because I’m aware of the reality I’m in and the little life I normally get each day is too precious for so many reasons. It’s so weird that people understood this in my much bigger city, but not here

You probably don't belong there. You are in a different mental place from the folks living around you with different priorities. It's not a matter of people "failing to understand" anything, it's that you are failing to consider the situation from their perspective. You'd rather feel smug and superior to others; so, you project your own views on to them and declare their lives somehow "wrong" or "bad". In fairness, they are probably judging you too. No doubt you are facing many people claiming that "you'll change your mind later" or other such drivel. If want you really want is the fast paced social life, a small town is probably not the best choice for a home.

I think under earlier circumstances, I’d have made an excellent parent.

Maybe, maybe not. The article touches on this, but I think it's important that it's explicit. One of the important things for having kids is wanting to have kids. It will change your life drastically. If you aren't ready for that, you will be miserable. If you're miserable and blame your children for that misery, you are going to make their lives miserable. I remember hearing the phrase "oh, you're never really ready for kids" so many times before I had kids. And yes, it's sorta true. However, it's also really, really bad advice. Kids will change your life (and you) in so many ways that it's impossible to explain fully and to be fully prepared for. They will also do things that you just don't have the mental framework to deal with; but, you slap it together really fast, because you have no other choice. "oh look at the cute baby in a onesie...wait, is that onesie also full of runny baby shit?! Why is it green, and what are those odd chunks? The fuck do I do now?" At the same time, you need to be in a stable personal and financial situation before you consider kids. If your personal life or financial situation is already unstable, kids are NOT going to help with that. You can be "ready" for kids, in that you have a stable life, but they will absolutely throw you a shit, piss and puke covered curveball now and again.

There are stronger people out there than me and I admire them for it, but I’m not willing to risk myself and another human to find out if this engine at 90% capacity has another secret gear.

Na, they're nothing special. Humans are amazingly resilient, we can adapt to just about anything. I'm willing to bet you would too, if that was what you wanted. That you don't is just fine and it's nice we live in a society where you are free to make that choice and have to tools to do so, without having to give up sex. But, also keep in mind that this is (for many) the life they picked. And they are likely happy overall. Maybe spend less time judging them and more time trying to understand life from their perspective, you might learn a bit about yourself along the way as well.