In rural America, getting someone into the parking lot isn’t much different than in the front door when the next box store is 10-20+ minutes away.

It makes less sense in the suburbs.

The average Costco ticket is $150 out the door. The retail margin is 11%, or $16.50.

Say you fill the car with 15 gallons, and they lose $0.25/gallon. That’s $3.75. If 1/3 of the gas station customers go in the store, they’re making $5.50 from retail, less the gas losses they net $1.75.

They make money, deny their competition business, and lock you mentally into saving money on gas and renewing that membership. That membership is half their operating income.

I’m probably being pessimistic. One thing with Costco is they are incredibly efficient, so I’m sure they’ve baked out cost and overhead. You can see stuff like how they provide the minimum number of garbage cans.