What businesses that operate in relatively commoditized product or service categories, earn high returns by competing on customer service instead of trying to be the low cost producer?

Many that come to mind - Amex, FRC, Chubb - compete on customer service but by segmenting the market and taking the high end.

So maybe customer service can best be applied to win in a commoditized industry by targeting a segment as opposed to the whole

Of course, the original premise of Amazon was to be lowest cost and most customer centric. So if you can do both, you too can build a $1.5T company.

But I was more interested in can you attack established commoditized industries with customer service as the differentiator.

Southwest Airlines is an interesting example of how to define whether they win on lowest cost producer or service. As with Costco, I would say the original idea was to provide a great consumer service at a low price, which was a function of their favorable cost structure.