You've chosen to post videos that are only viewable at the Vimeo site itself (or at least for some viewers of this forum). Not a complete roadblock, but if possible best avoided, as a courtesy to others.
Certainly some companies are more successful than others at volume sales, which doesn't imply that lower volume manufacturers are less successful, just that unit volume is not consistent across brands. Even the examples you posted are across a number of models where using the same Power Supply is unlikely.
But 10,000 is a LOT of units of ONE model. You would expect in order to limit the comparison to units with the exact same power supply, the volume would have to be higher still ... hard to say how much, but maybe 50,000/yr. Maybe more, maybe less, but definitely a lot more than merely 10,000.
I still say that your figures are too high in the vast majority of cases. Your premise that some are pocketing the difference in cost rather than lowering prices in a highly competitive market simply goes against the industry norms, and I don't see much evidence in the retail prices and in particular the street prices.
Probably more likely, and this is borne by more than 75 years of audio retailing, is the manufacturer will add features with the "extra" BoM money. The reason this is still the standard procedure is because it works at actually getting someone to pull out their wallet, which is the goal, after all.
Consumer Psychology is well understood and not much has changed since the 1950's. People are motivated to buy based on emotions, and one critical emotion marketers exploit is Fear. It's not just limited to over-the-counter medicine and body odour products. It is exploited in every product category, from new cars to ... well ... Audio.
The fear of not having some feature drives buyers to prefer complex products over simple ones. *
Few consumers are actually able to discern sonic attributes, and they are generally subtle features, which make them difficult to demonstrate, let alone market. If that were not true, reviewers and forums like this one would be of no earthly use; everyone would simply listen to the device, since sonics are the quality we actually use in an audio product, and buy the best sounding ones on the spot, which would be obvious to them. It is not obvious, and thus we have the market we do with the products we have.
* Back in the day, manufacturer's representatives, industry professionals and retail staff referred to these features as "bells and whistles", which meant features that did not add to the products sonic qualities, and in most cases degraded them. I don't know if the phrase is still in common use.
But given the choice, consumers inevitably chose the one with more over those with less. If you're trying to make a living, you either go along with it when choosing product lines, or go broke trying to sell the sonically superior ones. A good reseller was one that offered both and did his best to steer people in the right direction, but sold them what they wanted. If he didn't, they would just walk across the street and buy the inferior product anyway, which is a loss to him.
I am now WAY off topic, so I will end it at this last comment.