When today's top companies want to build a high tech product they put in place a production process that is so optimally designed that the process controls what happens. Part A gets prepared for part B. Part C gets inserted into C. You've seen it on TV. Each step is defined. Each piece is precise. In the end whatever is being assembled pops out exactly as planned. The process eliminates labor and material waste and insures quality.
Now think about how most homes are built today. All kinds of materials show up at a job site. People than often can't read & write cut up the materials and then bang them together. When something needed hasn't arrived constructors become gophers going somewhere to see if they can get what might be needed. At the end of the day a project with a dozen identical homes often will end up where each home is slightly different because they worked out that way in the field. That's where quality goes out the door.
That problem is further compounded by the fact that modern homes striving to achieve high levels of energy efficiency require tight tolerances and a commitment to assembly. A poorly constructed house is often the reason for higher utility and maintenance costs.