[pif]

> Which is, admittedly, a very HN assumption to make

No, it's your assumption that is wrong! You gave an explanation of several possible reasons, and you assume that people care. Actually, they don't!

The first site worked crappy and the second worked nice: the first site missed the money and the second one got it!

[bryanrasmussen]

No, my assumption was that the original poster hadn't ever worked e-commerce or they wouldn't have complained in a way that they thought it was inevitably due to factors within the sites' control that one worked nice and one worked crappy on this particular factor.

[ryandrake]

To an end customer, it doesn't matter if a problem is under the merchant's direct control or if it's happening upstream. He is the merchant's customer, the UX he sees is how the merchant is choosing to represent itself to their customers, and therefore the merchant, and only the merchant is accountable if that experience is crappy.

Whether OP actually worked in e-commerce is kind of irrelevant. I've never worked in e-commerce either, and if CompanyX fails to process my payment and I can't buy something from them, I'm going to rightfully blame CompanyX for that, not one of their service vendors.