And when "Just build more" doesn't work because private builders have no incentive to build a million dirt cheap starter homes for a mediocre profit and instead focus on building a few mcmansions?

We have a lot of building going on where I am. It's all for $500k homes. Nobody builds cheap one or two bedroom homes on tiny plots of land because the target consumer is more constrained and therefore far less profitable.

So much of the problems in the US right now is that capitalism optimizes for maximum profit, not any profit. It isn't sufficient in the US business culture to run a business that merely employs a bunch of people and produces things, because in the US, the "business" exists to be an asset class for the extremely wealthy.

So if the free market has no interest in serving people with less money than god, what do we do then?

I don't know why people believe there is a regulatory impediment to building a home outside of a city core. My dad is a contractor and he serves pretty much exclusively rich (gay) tech bros who fled california to increase our cost of living here in maine because nobody else can pay what they pay. His clients that don't fit that mold all inherited a good mid sized business or are well connected families. He does this instead of the plan he had a decade ago to refurbish or build about 10 new homes on a specific plot because it's literally twice as profitable at 1/100th the effort. Instead of working himself into an early grave, he can work 25 hours a week and live as upper middle class with his $100k pickup truck that is owned by his business.