Yes, that shit is warped and has knots in it. Yes, if you want the shit that doesn’t have warping and knots, you do indeed have to pay more money.
This is how all commodities, products, and services have worked, since the first time someone had the idea of trading one resource for another resource.
Please try to wrap your head around the concept. Better things cost more. This should NOT be blowing anyone’s fucking mind.
I haven’t torn into that many old houses, but enough to know that shitty building materials have always been shitty. If anything, at least building standards are better in many, though not necessarily all, ways than they used to be.
Eh. Once you get past a certain age in houses, you do start seeing some pretty fundamental differences. Like, wood density: the pine that’s used in essentially all residential building now is very light weight, with large growth rings. Most of that is from managed forests, where fast-growing trees have been favored over pretty much anything else. You also see that older homes tend to use larger pieces of lumber, because they didn’t know exactly what load limits were, and tended to over-build things (according to modern standards) as a result.
I lived in a neighborhood in Chicago that had always been very working-class, in a house that was constructed in the 1920s. All of the trim was, IIRC, alder. I tried to replace some of it, and it simply wasn’t possible to buy alder trim-even at the finest hardwood supply store in the city–that wasn’t full of knots and wormholes. 2/4 boards that were 8" wide–the width of the baseboards–just didn’t exist; there probably aren’t any alder trees available to logging companies that are large enough to get 8" clear boards out of.