For me, one big competitive advantage of Amazon is that i know that they will probably give me my money back if there is an issue (without me spending a ton of

For me, one big competitive advantage of Amazon is that i know that they will probably give me my money back if there is an issue (without me spending a ton of time wrangling customer support, and without me paying return shipping). For example, recently i had some items missing from Amazon and some items missing from Instacart. Refund from Amazon took a few minutes. By contrast, i've spent a very long time dealing with Instacart (and more hours sitting on hold, and weeks waiting for promised followups that never came) and no refund yet. Instacart is just an example; there are many other merchants with poor return policies (or poor execution of return policies), and many others with good return policies. The competitive advantage of Amazon here is that it's hard to quickly find out whether a merchant that you haven't used before has good customer support, which pushes you towards sticking with a merchant you know.