For the purposes of discussion, how does single credit card payment work? Does a user pay for each post and that is their “identity”?
What I am getting at is that there has to be some kind of account with a valid email to do anything beyond “buy this single item and never be seen again”. For example, collecting mileage points on that Quantas ticket you bought.
The case described only works if the customer buys once and walks away forever. Or buys so infrequently that they do not care. Neither of those are scenarios where Discourse would be of any use to that business whatsoever.