House prices are up quite a bit in areas that are rapidly building

That's reverse causation. Proper question is how much they were building the last three decades, and if it's outrunning new household formation* now.

There are places with cheap housing in the US, generally not in the good jobs areas but if you're retiring that's not so much a problem.

* that's when people move out of their parents' house or decide to not have roommates anymore

Well it's voters across the US, especially in urban areas with booming economies. Some places are trying to construct housing but can't cope with the influx of new homebuyers. Since there are no internal immigration restrictions, we have a national housing market with only partial local differentiation.