Because there is no such thing as a "new construction low end market". The finishings of a house or apartment aren't the expensive part of construction.

Look at the inputs to construction, there's no difference between low end and high end. Everything has to meet building code up to an extremely high standard due to modern building regulations. New laws mandate things like low-e glass, tougher insulation codes, solar panels (California requires them on new builds now), seismic, radon mitigation, AFCI, firewall requirements, etc. The average 50 to 100-year-old apartment has none of those things, and it would be illegal to build such a thing today.