Tech companies are structurally different to the plumbing/building business, you can't make this comparison.

Plumbing and building have static value. They will always do the same thing. The value of code is highly dependent on the context. SWEs are highly paid because they can create systems which can be reused and built upon over time.

Hiring an engineer to build a system doesn't make sense when it handles $0 in GMV, but makes a lot of sense when it handles millions in GMV. Tech companies are asymmetric bets.

This works up and to the point where people can't afford it (largely due to rising interest rates). Construction/remodeling is still in insane pricing mode right now. The bigger companies will string it out by offering financing but even that is limited again due to interest rates.