I happen to be in structural engineering, and I have to say that you clearly don't know what you are talking about. I'll tell you why.
Nowadays, and for a couple of decades now, there isn't a single european contractor who does not rely on prefabrication. Concrete structures tend to make this a bit harder to pull, but their building cost is so much lower than steel structures that the extra time spent on a project easily offsets costs. Even then, there are quite a number of prefab structural elements and modules, such as pre-slabs and composite slabs with profile steel sheeting, that help out a lot. With steel structures, even with composite slabs, it's quite easy to put up high numbers of floors in a limited number of days. The only limit that affects this is how fast you can hoist the beam and column elements, and how fast your crew is able to set the necessary connections.
I suspect that in the US it's even more widespread. There are companies which even put together factories to assemble entire houses in assembly lines, and steel construction is much more widespread than concrete.
So, your comment on the use of prefab techniques is obviously bullshit.
Then, regarding your conspiracy theory, it is once again bullshit. To start off, as any product on earth, housing prices aren't defined by construction costs, but only on what clients are willing to spend on them. Meanwhile, construction costs, with today's technology, basically depends only on what finishings the client wishes. As a demonstration, you claimed that 86k is such a great deal. Yet, that's the price Ikea asks for a tiny apartment with an area of about 70mÂ. This represents a unit cost of about 1228â/mÂ, and this without accounting for the price of the property and any licenses and services which are needed to build it. Knowing this, do you actually know what's the average unit cost for building a similar house on a property, including the price of the property itself? Between 500â/mÂ and 900â/mÂ.
In other words, your example costs at least twice as much to build than a regular house.
So, at least take your tinfoil hat off once in a while. The world isn't set out to get you.