That's striking. Building houses looks labor-intensive, but, if that's correct, labor cost isn't that large a fraction of the final cost.
Also, labor inefficiencies clearly exist, as protectionism by definition creates artificial inefficiencies, and it is rampant in all aspects of construction. It's easy to buy an off-the-shelf and cheap window air conditioner that uses a far more efficient variable-speed heat pump than the fixed-speed heat pump most central HVAC's use, but that same technology is rare in installed central HVACs, because the licensing and certification requirements impede the adaptation of newer more-efficient technology, despite the requirements ostensibly existing to increase its use, but in practice providing protectionism at the expense of modern efficient technology. There's similar effects with protectionism slowing the adaptation of longer lasting, safer, or less error prone infrastructure in other fields of construction like plumbing, electrical, framing, etc.…
Licensing and certification is also easily hijacked by NIMBYists, and because it's not based on actual safety requirements it can vary significantly from region to region, as is demonstrated by nationwide home builders having an efficiency disadvantage over those operating in only one region.
Granted, repealing NIMBYism and protectionism is nearly impossible, so it's not an effective means to reduce the costs of building housing, but it does demonstrate that there is a lot of inefficiency in the process. It also means that the field is ripe for disruption, because a concerted enough effort to sidestep NIMBYism and protectionism could break through and create a significant and immediate impact on the field, as for example, Trader Joe's did with wine importation, Southwest did with scheduled airlines, and Uber and Lyft did with town car services.
In practice, the single stage condensing units tend to be significantly more reliable. Inverter units require specialized control boards and semiconductors. The most advanced piece of logic in my condensing unit is a macro-scale electromagnet that keeps a circuit closed. I have several replacements sitting around my garage somewhere in a box. These components are brand agnostic so I could probably help my neighbors out too (or vice versa).
A single stage condenser can often survive things like a direct lightning strike. Also, if you live in a place like Texas gulf coast region, there isn't really a point to having a speed lower than 100%. You'd have 2-3 weeks out of the year where that would actually be useful.
You could potentially go from nothing to an entire nearly finished house in 2 weeks worth of labor, however because the framers, electrocutions, plumbers, siding, flooring, drywall guys are often all separate contractors and the shipping for all those materials are all on different schedules it takes longer. Or if a few guys are doing it all, they will lose a bit of speed by not being specialists for each task, but can make up that time having a more centrally coordinated plan of attack.
Even then the permits and design planning and choosing the windows and siding and flooring and all that is often still the biggest speed bottleneck.
The problem is that the costs of labor and materials from the past are behind us, and there are potentially no material cost and productivity improvements to be had. The costs are the costs and potentially unavoidable.
(I live in a house built from cinder blocks filled with concrete and rebar, like a commercial building. It was built by a commercial builder as his own house. It looks industrial from the outside, and nice inside. I'm fine with that, but most people are not.)