If anyone here has spend anytime in an assembly plant they would understand. It takes thousands of parts from all over the world to make a car. At some point they all come together in a final assembly plant.
It may be miles long and it may take days from a car to go from a coiled up roll of steel, stamped out and paint but as it rolls down the assembly line. Another one has rolled past every minute or less.
This is where fast assembly become obvious. They do not design and build them for us to rebuilt and fix them.