Lack of innovation.
Not much productivity increase in house construction has happened - see 1877 to 2020 comparison - https://youtu.be/ohudikjDmb0?t=1898
I think we can address productivity through our parallel build techniques. Also, the crowd wisdom in terms of absolute efficiency can help, as well as the automation such as robotic grading or 3d printed materials. It starts with going digital - complete CAD for auto BOM generation - see last point at https://youtu.be/ohudikjDmb0?t=2063 - which says that the industry doesn't do that yet. That is correct - we are one of the first people to do auto BOM generation.
Focus on product for a satisfied customer, profit will follow. CX - customer experience - matters. Star ratings - via Discourse plugin? Useful CX graph at 5 points - https://youtu.be/ohudikjDmb0?t=2343. Community experience - community features in any of our developments. How for a single house? Open house every month to meet new people for solving housing. Monthly open house at each location. Design Experience - cool features such as off-grid electric and water reuse,not to mention bottom line. Utmost control by YOU able to make additions or modifications - incremental housing. YOU own the house - you have the ability to understand and modify. Presentations about OSE at each location. Performance Experience - good water detail, moisture detail, comfort detail like non-squeky stair or floor. Sales Experience - service and support once you own the house! We can implement monthly open house in each state. We have a Forum for House Collaboration. Food plot - each house is landscaped with edible permaculture - nut, fruit, staple, to the point that individuals get involved in distributed nut breeding, etc.
Get out of a crazy amout of customization! Optimize core building blocks! Exactly. 
Software as a Service
Digitize everything - services includes design, docs, scheduling, BOMs. Yes, that is our software as a service.
Compact plumbing saves 1000s? That sounds familiar.