In attempt to turn this teachable: the costs that go into housing aren't just labour, whether skilled or unskilled. It's a number of economic goods and services, each of which has its own price dyanmic.
The chief cost of housing is land, and that follows the laws of economic rents and assets, in two principle ways:
- For goods subject to rents, that is, where supply is nonresponsive to price, any surplus value accrues to the seller rather than the buyer. The marginal price tends toward the marginal value rather than the marginal cost.
- Moreover, as an asset, land is subject to the general behavioural tendency that holders of assets will tend to act such that the value of assets inflates. This is through constraining supply, sale, credentialling, regulation, certification, and other elements. This shows up in zoning, construction, certifiction, lending, insurance, and other obligations or limitations on new construction.
- Unskilled labour is subject to wages, which tend to fall to the level of marginal cost, if not below that. Incidentally, in a simple society of labourers vs. rentiers, surplus value accrues to the rentiers as a case of the law of rent vs. the iron law of wages.
- Skilled labour wages deviate from those of unskilled as skill itself is a rent-generating factor, and hence skilled labourers can command somewhat higher wages. (Adam Smith's discussion of the five factors involved in the wages of labour are a fascinating read.)
- Materials follow natural resource pricing, which ... is very poorly understood by modern economic theory, but tends to follow the marginal cost of provision by the marginal supplier. That is, the supplier with the highest viable cost structure sets the market price for the commodity. Perversely, when the market is oversupplied, prices often fall (expected) and production rises as the only way producers have of meeting their own fixed costs is to produce and sell more at the lower price. (This occurs because marginal costs may fall below fixed costs.) The situation is not long-term sustainable, but may persist for a substantial period of time. For purely extractive resources (mining, gas, oil), the replacement cost of the good is not factored in at all, and market prices may be hundreds to millions of times below any rational fully-accounted cost basis.
Net productivity of labour has increased markedly. The land-cost of housing has increased far beyond that. Materials have shifted in several ways, with numerous older materials having been replaced by nominally-cheaper modern equivalents. Restrictions on construction methods, materials, designs, etc., impose additional costs and constraints in design and building as well.
The question largely reveals a large ignorance of the factors involved.