I must admit to having a slightly different perspective, as we once bought a semi-custom boat (real - not a model!) The manufacturer made it, but didn't do a great job of "final test and inspection". The dock guys at their marina were expected to finish tuning air-conditioners, radios, drives, and various other items. We finally got them all sorted, but it took a while and delayed delivery.
I often get the impression that Accucraft feels the same way - especially when they announce a cut-off of March 31 for a particular model (EBT #12) meaning they want to know how many models to make. They aren't doing mass merchandising, and the models are all slightly different; more semi-custom manufacturing.
However, I'll bet Accucraft would look at this thread with concern and regret. I doubt that they want to provide a product that doesn't work out-of-the-box. Correct me if I'm wrong, but is this confined to live steamers? Don't the electric locos work most of the time? And isn't it a random problem: some folks locos work perfectly and others are missing bits, are damaged in shipping, or just don't work right?
The problem, IMHO, is that they can't teach the factory to do the final QC and test before shipping. It can't be a cost/price issue, as the cost of doing it there before packing the loco has to be fairly small. This suspicion is confirmed by the random packing issues: some locos are packed beautifully, and some folk complain that parts are scattered all over the box.
I know they test the boiler, as they send a certificate. But I don't think they run a real live steam test. Maybe we should petition them to always steam the loco before packing and shipping. That produces other issues, such as damaging the perfect finish with the flame, and purging the gas tank completely afterwards, but they aren't insurmountable.
