Big Al,
I believe Honda's parent company owns the factory, and the workers are their employees. Leupold and some other optics manufactures actually own the plant where all or some of their optics are assembled, and the employees are their employees. Others do not necessarily own the plant nor are the workers their employees. Instead, they negotiate with the owner of the plant a fee to assemble their product. They may even negotiate with the company to provide or secure the components necessary for the product.
There are only a few manufactures of automotive and industrial batteries. These manufactures will produce batteries according to the specs of each individual company, and will use a manufacturing process that will still allow them to make money (or not lose much money) on a particular line.
As to parts for automotive and heavy equipment, just because a part has the same design and is for the same parent company does not necessarily mean it has gone through the same QC and inspection process. Some companies will actually do different runs for some critical parts, and the parts for the higher dollar product will quite often receive more QC and attention to detail in the manufacturing process. It is not likely a new employee will be trained on the higher dollar product like they will be used for training on the lower dollar product. If there is a possible problem with the raw stock and there is not time for new stock to arrive, it is very likely the lower quality stock is not used for the higher priced item.
There is a company who supplied parts to both the firearm industry and engine companies. Years ago, who the part was for made a difference in the QC and who worked on the line for that part. I am not sure if that is still the case, but I would not be surprised. I also would not be surprised it this happens at many if not most companies.