What on earth is the point of limiting membership to such random and specific groups?

Government Regulations[1]

> According to the Costco U.K. website, memberships to those stores are only available to certain groups of people. Since the store is classified as a wholesaler, this complies with the U.K.'s wholesale store laws. These dictate that wholesale stores are only accessible to those working for select business sectors.

[1] https://www.thedailymeal.com/1483679/costco-uk-membership-re...