I think the answer is that a credit card company is vouching for you when you make a purchase. The seller does not know you, but they know the credit card company, and they know the credit card will give them their funds. The credit card company in turn knows you, and has deemed you credit-worthy. This is why it's called "credit" ... from the latin credere: "...
Our Bitcoin HD module for Prestashop answer all your questions. It is based on the HD (Hierarchical Deterministic) wallet so your bitcoins are safe and no need to third party.
Notice that I am the developer of Bitcoin HD module.
Link to the module page :