I wonder if the flag gets reset every so often if the device doesn't think it's in the US for a long period of time. I've heard Apple considered that for some of the other EU restrictions
Probably not to account for people spending lots of time outside the US. The main restriction is not selling items with particular features outside of approved countries but them getting used after being bought elsewhere isn't usually a big deal. India doesn't care about my Grandma wearing her hearing aids because they're not approved in India and if the government doesn't care where's the incentive for Apple to break functionality for customers?