No country flag icons?

According to Standard Icon Names, there are Standard International Icons:

Name	Description
flag-aa	The flag for the country with the ISO 3166 country code AA. All flags should use ISO 3166 two-letter country codes, in lowercase form, as the specifier for the country.

Is there any reason Breeze theme doesn't contain that?
It might be useful for implementing new QML keyboard layout applet/KCM page.