Hi Kate,
Yes, they are geo-targeted versions of the site, but the idea would be to create multilingual versions of the site for other territories in the future, so the hreflang + country targeting seemed to be the best option to allow for future expansion in the site framework.
The site was working correctly for about a month before Google started showing country subfolders as sitelinks for the main domain. However, the correct locale sub-pages are still being shown for other search terms. Seems to be an issue with the home page or branded search, where the correct country homepage is no longer being shown as the main result, and instead as a sitelink beneath the domain.
Ro