The company I work for, gets good delivered by sea quite often. I have seen sea-containers getting dropped by accident and from the reaction of the guys handling the container, I did not get the impression that I was witnessing something rare.

It is very well possible that a large batch from Yamaha was handled improperly on its way to/through the US. I think it's nonsense to suggest that Yamaha willfully ships instruments that are not checked thoroughly, or in any other way below Yamaha standards.