Machines with interchangeable parts can now be constructed with great economy of effort. In spite of much complexity, they perform reliably
I would argue that quality and quality control diminishes heavily when interchangeable parts are produced cheaply and at high intervals. I understand that they perform reliably for a short period of time, but there is a reason we see older cars at a high volume, and its because they were built with higher quality materials and at a slower rate to ensure a quality product.