ZIP code verification is commonly used for credit card authentication at gas pumps in the US, especially before the advent of chip & PIN.
This is immensely annoying for Canadians who drive their cars to the US, although there are some built-in workarounds supported by the credit card processor such as punching in the 3 numerical digits of a Canadian postal code followed by 00.
When credit card companies started requiring pin&chip at stores in the US a couple of years ago, there was a special exception for gas stations, I guess because their pumps are a pain to retrofit or something. As a result, it’s an easier target for fraud.
This is immensely annoying for Canadians who drive their cars to the US, although there are some built-in workarounds supported by the credit card processor such as punching in the 3 numerical digits of a Canadian postal code followed by 00.