Actually there is and it's not done by the vendor.

Once a charge authorization goes through, the credit card company holds the allocated funds off the total allowable line of credit until either the credit is processed in favor of the vendor, or cancelled.

In turn the cancellation is not immediate. So if you put in a charge and then cancel the sale, it can be up to 2-3 weeks before the funds are released off the credit card.

This is normal operating proceedure.

Now in the case of on-line vendors the charge goes through immediately as on-line transactions are handled in an automated manner.

However a human must check the ship-to/billing address and verify that a P.O. is not given. If the latter is done, then they ask for the additional verification.

If the person declines to give it or cancels the sale, the purchaser ends up with a charge against their card until the credit is negated by the vendor and the credit card company.

So the end user ( as the original poster saw ) sees a charge on their card, but if they cancel the order, they may never see any actual entries on their statement... or at worst they will see a charge followed by a credit on their invoice.

It's pretty standard fare and has nothing to do with anyone ripping anyone else off.