There's an argument to be made for being able to turn on a feature for a certain segment (e.g low revenue users in Italy) so you can see what the business/performance impact is.

Ofcourse you don't want users to lose the feature once they exceeded your revenue threshold or cross the border so you'll need to implement some kind of tracking. Your analytics and error tracking also needs to communicate with the feature flag service.

Definitely not rocket science but more complex than a environment variable.