Final preproduction models are not always the same as production. smaller quantities are not always made the exact same way as full production.
True, but only for companies that suck. Those that know what they're doing follow the AIAG PPAP methodology and make sure their products submitted for an approval warrant are made using production-worthy materials, processes, tooling, people, and at the anticipated full production rate.
And also have a ramp-up/maturation plan to make sure any last minute issues get caught and addressed so the customers don't have to.