I think it depends on the place but one observation is to notice what builders are choosing to build. In my area at least the majority of new construction is either cramped subdivisions with $600K+ homes, luxury apartments, or 55+ maintenance provided housing. All of these categories are not what the general populace is looking for, especially first time buyers or new entrants to the market. But I'm guessing the margins on these properties and rentals are much higher.
I think developers don't want to waste their efforts on affordable rentals or starter homes. They have block of land X, so they figure they can get Y% more return by building properties with rents in the top quartile for the area.
This is an average including the most expensive areas of the county. Homes are still very affordable in areas like the Midwest (under $200k and sometimes under $100k).
No the fuck they are not! I am tired of idiots saying this. I live in the Midwest and I assure you that they are not. We have too many people moving in from the coasts buying sight unseen and causing our prices to sky rocket. And our rents aren't any better. Kansas City, MO had the highest rent hike in the country. Our cost of living is getting closer to that of the coast but our pay is not.
My job brought me to Indiana last year from Denver. I thought I might be able to afford a home here. Nope. I'm paying the same in rent for older apartments. The homes face the same pricing issues as the rest of the country. Additionally, as you mentioned, folks are coming in with cash over the asking price. The whole thing is fucked.
They have to be affordable for the local population as well, not just an average income. Incomes in places with lower cost housing are lower, too, so raw numbers aren't meaningful.