Something else I am surprised no one has brought up.
The newer planes are designed to much finer tolerences, requiring precision machines to achieve those tolerences. Obviously the first few built for certification will receive more care to ensure that it is put together properly. But what happens when the planes go into production and become "mass produced"?
We have seen reports of Boeing accepting components for such newer planes that are not made according to specifications. When parts that were supposed to be computer cut were cut by hand. Where holes do not match up and have to be redrilled. Where parts that do not fit are hammered in to make them fit.
https://www.sbs.com.au/news/sites/sb...ranscript.html
A carefully put together aircraft that fails at 99% highest test load may later become a bash-it-in-to-make-it-fit aircraft that fails at a much lower load .