The incentives of the bank is to cut fraud.

Fraudulent transactions will eventually cost the bank (when they would have to reverse/reimburse it and eat the loss). A denied transaction only results in an angry customer who will quickly forget after they complained - so the customer bears the brunt of the externalized cost.

Therefore, the bank's incentive is to err on the side of more caution, and deny transactions when finding false positives.

When someone disputes a charge and wins banks charge processor and the original merchant. The bank won’t loose a penny, merchant will.