I think it's just too little volume for the savings to trickle down. The majority of houses built today are still done in traditional ways, very few new homes are prefab homes (in the US and Europe). Most of the people buying prefab homes in these regions today are doing so because it's faster (weeks to months instead of 6 months+) or easier (only need heavy equipment on site for a couple of days), so those benefits can be sold as a premium service.
I am having a new home built right now, and the costs are roughly 50% for the 'shell', e.g. to the level where you have a water proof building with roof and windows, and 50% for all the work inside. For the 'shell' it's actually quite simple work, and doesn't take too much time, it's basically just LEGO :D The complicated parts like doors and windows are made off-site, so when they arrive you just need to fit the house around them. We are having a traditional A-style roof, so the roof joists are made off site too. Most of the costs are on the materials, not the work. Materials that reduce the work like ICF or SIPPs also increase the material costs - in my case to a point greater than what you save in labour costs.
For the interiors nothing can really be prefabricated at volume, as everything is completely custom to the project. That's not going to change unless these Japanese standard measurements that article talks about spread elsewhere. For large projects its a bit different though, I've heard for hotels they sometimes prefabricate large parts of the bathroom and lift it into place before the next floor is put on. That makes sense though as you are building a few hundred things that are exactly the same.
I am having a new home built right now, and the costs are roughly 50% for the 'shell', e.g. to the level where you have a water proof building with roof and windows, and 50% for all the work inside. For the 'shell' it's actually quite simple work, and doesn't take too much time, it's basically just LEGO :D The complicated parts like doors and windows are made off-site, so when they arrive you just need to fit the house around them. We are having a traditional A-style roof, so the roof joists are made off site too. Most of the costs are on the materials, not the work. Materials that reduce the work like ICF or SIPPs also increase the material costs - in my case to a point greater than what you save in labour costs.
For the interiors nothing can really be prefabricated at volume, as everything is completely custom to the project. That's not going to change unless these Japanese standard measurements that article talks about spread elsewhere. For large projects its a bit different though, I've heard for hotels they sometimes prefabricate large parts of the bathroom and lift it into place before the next floor is put on. That makes sense though as you are building a few hundred things that are exactly the same.