Note that in this case, the credit card company punished a merchant who wasn't even connected to the fraudulent transaction.
The rule of thumb is that the more lenient the company is for the customer, the more harsh they are on merchants, the higher their fees for merchants, the more reluctant merchants are to accept them, and the harder it is to find a merchant who will accept the card.
(Note how many businesses accept Mastercard and Visa but not AmEx).
Note that in this case, the credit card company punished a merchant who wasn't even connected to the fraudulent transaction.
The rule of thumb is that the more lenient the company is for the customer, the more harsh they are on merchants, the higher their fees for merchants, the more reluctant merchants are to accept them, and the harder it is to find a merchant who will accept the card.
(Note how many businesses accept Mastercard and Visa but not AmEx).