[mindslight]

A loss leader isn't a monopolistic practice. They can be related, for example video game consoles can be loss leaders, to build demand for a monopoly on games for that specific console. But that relies on the sticky market effect from a customer owning a particular console, whereas the loss leader on gas has to convince the customer to visit the store every time.

If anything that Alabama law seems a bit questionable. As long as gas stations have card readers where you don't even have to go in the store, converting gas customers to convenience store customers seems like quite the uphill battle to me.

(modulo the surveillance issues of using payment cards)