Now I'm curious what the criteria are. Oxbridge graduate?
https://customercare.costco.co.uk/app/answers/detail/a_id/85...
Apparently, by targeting the Wholesale market - plus a limited range of general consumers, they are able to class their stores as wholesale warehouses, which can be opened in locations where a general retail store wouldn't be permitted. That makes purchasing or leasing land for the store much cheaper.