So I'm more confused than ever! not hard I know.
So having a quick scout around the internet I found a number of articles pertaining to how a tyre is actually constructed. Generally you have a casing that forms the skeleton of the tire which is made of fabric. Manufacturers use the term TPI (Threads per Inch) to explain how many threads make up a single layer of fabric, anything from 60 tpi to 120. At 60 tpi the threads are thicker than 120 tpi threads. It's all explained a little bit better here:
https://www.cyclingnews.com/features/what-is-tpi-in-bike-tyres/
After the casing is built, there may be a layer of puncture protection put on top before an outer layer of rubber is put on, then it's all bonded together. I have a pair of Teravail
Rutland tyres on my gravel bike, set up tubeless and running at 32psi. With Teravail, they offer a light and supple casing and a Durable casing for their tubeless tyres, the difference being, the durable has extra layers of sidewall and puncture protection added.
https://www.teravail.com/articles/whats-in-a-tire-all-about-casings-and-compounds-pg1233.htm
So sidewalls can be built in a variety of different ways for tubeless, just like with normal tubed tires. When it comes to tpi, interestingly Schwalbe Marathon tyres are 65 tpi and the Teravail Rutland Tyres I use are 60 tpi, so no real difference at all. There's no mention anywhere, aside from bead construction, of tyres intended to be tubeless, having a different construction technique.
So all in all, I really don't understand why there is this perceived difference between tubed and tubeless, or if indeed there is one looking at how tires are made. The only reason I can speculate as to why my Rutland tyres don't last nearly as long as Marathons, for example, is that the rubber compound is fundamentally different. The Rutlands for example, probably use a much softer compound in order to provide good grip off-road and combined with a lot of off-road riding, they wear down much quicker. Certainly this has been my experience, that no matter what the sidewall construction of my tyres, I've never had any noticeable damage or wear on them, instead I've only ever retired my tires when the tread has become too worn or damaged. So the different tread compound is not really a component of them being tubed or tubeless, rather a result of their intended end use, or at least that's my perception.