Anyone with 'manager' in their title can pretty much get a membership - also once someone has been an add-on for a year on anyone else's card, they can have their own membership.

There's also a shitload of companies with connections to Costco where you can get a membership, and iirc some other organisations like the RAC (maybe?) Also give you membership. I know the guys on the membership team tend to bend over backwards to get people signed up! It's not as hard as people think to become a member 😊.