You illustrate the misunderstanding a lot of people have. You are conflating the completion of payment between end users with the settlement. In Bitcoin they are one in the same. The issue is not whether the payment takes 1 minute or 20 minutes to complete it is whether settlement is incidental to the payment or deferred. Deferred settlement creates credit risk.
The issue of risk of non delivery of goods is one that is a insurance service someone provides on top of a payment system and isn't particularly relevant to this discussion.
Physical exchange of cash and Bitcoin are the only two payment systems that I've ever heard of that don't have counter party credit risk in some form.