I'm in Calgary, Canada, but I don't expect it's a particular outlier in North America on this front.
Houses become tear-downs mostly based on economic viability and comfort, not based on their habitability. I lived for ~10 years in a desirable inner-city neighbourhood that was originally bungalows from the 1960s. In the time I was there close to 50% of the bungalows were torn down (or trucked off - last I checked the value of the physical home being trucked off was in the $10k range after costs) and rebuilt with either larger homes or denser units.
My landlord bought a second bungalow in the area and did a full reno, keeping the guts, and by his math he was basically break-even per sq ft over tearing it down and building bigger/denser.
To your original point, the 1960s bungalows and the 2010s homes (or 1960s home renovated to modern standards) do have vastly different prices. Modern builds are much better from so many perspectives - electrical, plumbing, layout, lighting, insulation, heating/cooling, air quality, fire resistance, etc. (including ways that can't be upgraded even with a gut job - e.g. you can't upgrade from 2x4 framing to 2x6 framing for extra insulation space) - it would be deeply weird if all of those improvements made no difference to prices.
Houses become tear-downs mostly based on economic viability and comfort, not based on their habitability. I lived for ~10 years in a desirable inner-city neighbourhood that was originally bungalows from the 1960s. In the time I was there close to 50% of the bungalows were torn down (or trucked off - last I checked the value of the physical home being trucked off was in the $10k range after costs) and rebuilt with either larger homes or denser units.
My landlord bought a second bungalow in the area and did a full reno, keeping the guts, and by his math he was basically break-even per sq ft over tearing it down and building bigger/denser.
To your original point, the 1960s bungalows and the 2010s homes (or 1960s home renovated to modern standards) do have vastly different prices. Modern builds are much better from so many perspectives - electrical, plumbing, layout, lighting, insulation, heating/cooling, air quality, fire resistance, etc. (including ways that can't be upgraded even with a gut job - e.g. you can't upgrade from 2x4 framing to 2x6 framing for extra insulation space) - it would be deeply weird if all of those improvements made no difference to prices.