We did a lot of research and we were initially thinking of prefab for our home, but we finally decided to go for full custom design. In the end, prefab can really make some costs more predictable, at the cost of some flexibility in the design. Cost-wise, it was almost the same (for our case) but construction would've been faster and more probably more controlled in terms of budget.
The land for a SFH inna "sought after area" is at least $300K and probably much more.
https://www.nahbclassic.org/generic.aspx?genericContentID=26...
Real examples:
I had a gas leak. The pipe was hidden behind all the kitchen cabinets. 1/3 of the cabinets had to be removed to get to the pipe.
At a new build one guy was sloppy and put a nail into a water pipe. The entire wall had to be redone.
You don’t have to save cost if you can increase reliability and speed.
there is, I think, a pretty strong correlation between reliability of a solution and the future maintainability costs being lower.
Prefab doesn't solve that one hundred percent, but I assume it would significantly increase build speed and predictions of completion date.
It's also worth noting that even for a "solved problem", driving down costs is still beneficial in the end.
What is acceptable is an important question. I've been in houses from 100 years ago, most had significant remodels that clearly did things not anticipated originally and so it is obvious to a knowing eye where the different parts are. On the other hand, construction is expensive and the throw away culture seems wrong too. I'll let you decide where the trade off should be made.
Here is a developer of prefab houses showing their plus energy house (meaning it produces more energy than it requires to live in): https://www.hanse-haus.de/en/prefabricated-houses/energy-eff... - these are not made out of aerated concrete though, they use timber panels.
Land is quite cheap in many parts of say, Australia or Japan due to low population density, but in big cities the prices increase again.