Replacement cost tends to factor greatly into how much things stick around. Cheap stuff gets replaced over the years, expensive stuff gets maintained and fixed up so you get a lot of survivorship bias.

Additionally, labor becomes cheaper relative to materials the farther back you go in history so older stuff has proportionately more labor put into it. Having a bunch of fancy ornate wood work in your house was the 100yo equivalent of having a bunch of granite countertops.

But that's the thing, even the fancy stuff today doesn't have much of the fit and finish of modest stuff in the past. Go find a new construction apartment commanding top of market rent in your town, and I bet you can hear your neighbors through those paper thin walls and the appliances are new, but the cheapest ones possible. Mansions became McMansions. Compare the Broad in LA to the library build 100 years before; the materials in the $140mm Broad are bare concrete and latex paint, while the LA central library looks like a Byzantine palace.

Old woodwork in houses is pretty much always excellent. Why? There was way, way more top-quality lumber available (they'd "throw away" giant near-perfect timbers in framing, including using huge load-bearing pieces along foundations that'd cost thousands of dollars each today, assuming you could find something similar at all) and you couldn't get away with doing bad woodwork—because there was no air conditioning and heat wasn't as good as it is today! Badly-installed woodwork that didn't have great corners and joins, didn't account for wood grain and cut and position pieces accordingly, use properly aged lumber of a suitable quality, and so on, would simply fall apart between temperature and humidity swings over the years, probably so fast it'd come back to bite whoever did the shoddy work in the ass. Well-build wood finishes, meanwhile, can break a century and still be almost perfect, with little or no maintenance (aside from repairing outright accidental damage, of course, and keeping water from getting in the structure). But we don't really make those anymore.

If someone wants really nice wood trim, mantlepieces, panelling, and such in a modern house, it seems they usually loot it from an old house. The materials and work are too expensive now to make it from scratch. Ditto doors, of all things. Modern interior and exterior doors are awful compared to solid wood doors that were common not even that long ago, but, though you can still buy them, new solid doors are impractically expensive, so buying salvaged old doors usually makes more sense.

Lived for a while in an apartment building put up about 1910/20, so indeed pushing a century. Solid oak doors. The banisters (railings on the stairs) also solid oak. Duplicated would cost a fortune today with newly cut wood.

> Go find a new construction apartment commanding top of market rent in your town, and I bet you can hear your neighbors through those paper thin walls and the appliances are new, but the cheapest ones possible.

Not really true, I rented more upscale apartment once and, unlike my previous apartment, I couldn’t hear neighbors due to much better sound isolation. Appliances and cabinets were much nicer too.