Costco is not selling gas at break even or a loss. No one does. They sell at a lower price (and still profitable) to generate traffic and convince customers Costco is wholesome and good - so they spend more money there. They also make it up in volume - there is always a line.Costco sells its food at a break even or at a loss I believe.
Wholesale price of gas in LA is $2.32. Its likely similar in Oregon - EIA stopped publishing individual states a couple years ago. But of course everyone believes its the evil big oil companies gouging because that is what the mainstream preaches. https://www.eia.gov/todayinenergy/prices.php
The Costco here - which is in the city - is often more expensive than my local stations out here in the boonies.