Yes, I get how the iPhone could identify real AirPods, but my point is how would it differentiate fake AirPods from any other 3rd party buds (that weren't pretending to be AirPods)? Surely from a technical point of view, they're both the same thing? It's not as if the iPhone can see that they look like AirPods or knows about the fake Apple box they came in.
And to add - how does Apple decide at what point a legitimate third-party set of buds that's 'inspired' by the AirPods design constitutes a fake? There are plenty of white buds that come in white charging cases on the market now, some from very reputable manufacturers, that clearly aren't trying to fool anyone into thinking they're AirPods.