The thing is you can save a ton of money on a few non-food items to make it worth it. Just over-the-counter medicines save me a huge chunk of the membership fee. Then there are just random household goods: paper products, trash bags, dishwasher detergent, etc.
Renting a car once a year through Costco Travel is worth the membership fee.
It's great for canned goods and anything bulk for cooking, see: salmon.
Glasses is another place where the savings are astounding
Their pharmacy is A+.
I get my dogs seizure meds there and they're about $10 a month but at a regular pharmacy they'd be $300+.