@goldielocks Yeah, I'm not questioning $100/sq ft....my interest now has transitioned largely to how builders where I live are building for so cheap (e.g. $100ish/sq ft including a quarter acre of land in a city).
Okay,
How they do it here:
1) Reduced capital cost of large systems -- eg., they put in baseboard heaters instead of central forced air. In the past, only apartment blocks here had baseboard electric heaters (as supplemental heat). Boom! instant $7000 savings to contractor, higher heating costs to the homeowner (over natural gas).
2) Repetitive construction -- trades can move FAST when they repeat it 15 times on the same home plan.
3) Severe reduction of fixtures / electrical plugs, versus what you would put in if you decided at the start.
4) Steep discounts on materials provided. They negotiate hard with suppliers, because they buy a lot of the same thing, and know what looks decent for very little money. (may wear faster).
5) All one paint colour inside. one coat, fast paint job.
6)Put in the least number / level of items they can get away with on a whole home basis, putting money into kitchen and eye catching items (many of those will be an upgrade cost though).
7) Orange peel wall finish (very fast, quick to hide the seams)
8) Builder grade windows and doors. -- most people don't notice.
9) Few decks / outdoor improvements, few hose bibs, etc -- everything is an extra.
10) The floor plans are often deliberately designed to fully use full sheets of drywall, with minimal cutting, likewise the studs and other building materials dictate the room dimensions.
11) Often few angles to reduce finish work.
12) Everything is very well planned and coordinated from the start. The plumber for the kitchen knows exactly when he is going in, and what he needs to do / bring each time. Good builders will have great instructions for the trades, who won't have to figure out solutions to unforeseen interface problems. This is due to the limited number of home plans that are used over and over again.
13) Large enough building teams that you can use quite a few apprentices / junior (low skill) persons fully, and have the highest paid persons ONLY completing the skilled work, and quickly.
14) limited travel time for the trades -- can't finish task x on the first home? no problem, walk across the street and work there until the painter / plumber / carpenter finishes his work on the first home.
15) Likely no architect needed on a per house basis. After the first few homes built, the same plans / details are used over and over again.
etc. etc. etc.