You need a membership to get through the door, right?

Or they consider it a marketing channel for their memberships. Costco stores aren't exactly in convenient locations if you aren't already a member. And someone who would go to all that trouble for a cheap hot dog might as well hit up Ikea instead. For starters the Ikea food court has more than 3 things on the menu, as well as coffee and tea.

Depends on the store. Some stores food courts are outside where they check for membership and some inside.

> Costco officially restricted food court access to members in 2020

How much that's enforced is store by store, Costco makes a lot of profit off of memberships so there's an incentive to having non-members have a positive opinion of the store so that they one day become paid members.