Because soccer is beholden to the rules of Association Football, meaning the UK gets to decide what qualifies as a country. In the meantime the IOC has a rule that a NOC only qualifies as based along the lines of the governmental body which treats with the UN. There are some dependent territories who get special treatment (e.g. Bermuda, Puerto Rico) which traditionally sent teams before the rule on must treat with the UN directly and are grandfathered in.
Because soccer is beholden to the rules of Association Football, meaning the UK gets to decide what qualifies as a country. In the meantime the IOC has a rule that a NOC only qualifies as based along the lines of the governmental body which treats with the UN. There are some dependent territories who get special treatment (e.g. Bermuda, Puerto Rico) which traditionally sent teams before the rule on must treat with the UN directly and are grandfathered in.