Merchants trust them because it is simply a cost of doing business.
For instance, in a B&M (Brick and Mortar) store, when you price an item you add in things like, utilities, payroll, profit and shrinkage. In other words in a B&M store you EXPECT people to steal from you and pass that cost on to your customers.
With a credit card the same example holds up. This is why places like Walgreens don’t require a signature on most purchases under $50.00. If you were to dispute the transaction, Walgreens would lose, as it has no signature.
But the cost of getting the signature and the time involved etc, is less than the amount of chargebacks they have.
Another example, I was the asst controller at a hotel and in the last five years we had THREE chargebacks. that’s a ridiculously low amount, but for some reason people disputing credit card fraud at that hotel was low. So it made no sense to have a high level of credit card clearance.
The more scrutiny a credit card is subject to the higher the cost to the merchant, but it also means the longer it takes to process them, but you get more security in case of fraud.
So why pay for something that’s not needed.
Merchants simply have to take credit cards in this day and age. They would lose too much business. If it’s a fraudulent and they get an approval from the credit card people, they get paid anyway and the bank absorbs the loss.
So if I work at ACME company and Mr Coyote uses a credit card he stole as long as I, as a merchant, verify the signature, and get an approval code it is the BANK that is the loser not the merchant.
Of course the bank merely takes the loss and ups the charges at its bank to cover the loss.