They don't have a cashback program here.

Ah I didn't realize cashback was US and Canada only. Purchasing over $6000/year will cover the fee, which isn't cheap if you don't do much shopping there. The rewards site has a table with reward estimates: https://www.costco.com/executive-rewards.html

In the US, the standard Costco membership does not offer cash back, the premium membership does. If you don't have the auto-renewal set up, they'll tell you which version is a better deal based on your purchase history from the prior year.