From a consumer's perspective all I see is a bunch of high end cell phones with very similar features and priced the same. Nevertheless, many people decide to buy the Samsung flagship phone over the Sony, LG or HTC.
Better economies of scale could be the reason if they decided to price their phones lower, but they don't. So that it's not the reason why people are choosing Samsung.
About the competent design, I don't see the Galaxy being superior to the HTC one or the Z2.
An economy of scale doesn't necessarily mean they price their phones lower. It could mean they offer more expensive products at the same price and with the same profit as their competitors, or offer equivalent products at the same price but higher profit than their competitors.
That's right. But they do not offer a better product, the flagship phones are all pretty much the same. And there is no reason why a higher margin should turn into a higher market share.
Better economies of scale could be the reason if they decided to price their phones lower, but they don't. So that it's not the reason why people are choosing Samsung.
About the competent design, I don't see the Galaxy being superior to the HTC one or the Z2.