Chris your whole post was interesting so I wont repeat it

Focusing on the builder assist concept, area in any workshop be it job shop, builders yard shop, construction or production shop will cost by the area and the day, so it presents several difficulties.

1/ that shop time by the day and by floor area is in itself a cost
2/ the scheduling of a queue for builds may also be a factor
3/ suitable insurances might be a bit of a nightmare

Im not dissing the idea, I just think some stuff would have to be worked out