I wonder how much (in the US) sales tax impacts this? Most US states have significant sales taxes on manufactured goods, including prefab housing.
If I pay for someone to build onsite, I pay the labor cost. If that same labor builds offsite and the finished product is delivered, I must also pay sales tax on that labor.
If I pay for someone to build onsite, I pay the labor cost. If that same labor builds offsite and the finished product is delivered, I must also pay sales tax on that labor.