I suspect your familiarity is with areas that are much higher cost than average. I've owned houses in two different MSAs in the top 25 in the US and the land value was much lower than 80% of the total value. Land value is also very demand-driven though local zoning regulations (multi-family units, proximity to commercial zones, etc.) do drive some of that demand.

Yeah, my familiarity is with the city proper, original streetcar suburbs, etc. I know modern suburbia is cheaper the further one travels from the city center, but this seems just another high price.

Also, I judge the lot value by how much it would sell for without the house. The price for empty (fill-in) lots is ridiculous. I'm all for the market setting prices, but this isn't that. This is Federal interference and local building lobbying.

If only there were some technology that would allow multiple homes to exist on a single lot...

That would just be priced into the lot.

People are going to spend 35-50% of their incomes on housing.

Federal mortgage regulations are strongly biased against that. And in the USA the Federal gov't. owns the mortgage industry.

Where is this? In Seattle the cost of construction is around $250-300 per sqft assuming mid-range quality of materials and a flat(-ish) site. You'd need to spend between $200-$500k to buy a lot in Seattle. So a reasonable 2,000 sqft house is going to be anywhere from 70-50% of the cost.

That's a new house. The weird thing is how often old houses don't sell for much more than an empty lot in single-family home neighborhoods. Although I'm not familiar with Seattle. I've lived in various parts of Florida, Denver (long ago), Michigan, Texas, etc. Mostly Sunbelt.

There's not many vacant residential lots within city limits in Seattle, but the ones out there are definitely cheaper than buying a lot with a home, new or old, on it.

Is that the cost for house? Do you have any data on building prices per sqft for High rise building?

Yep that's for a house. I don't have any costs for high rises.