The point about why USA passports don't get a 'stamp-exempted stamp' (which I'm totally in favor of - no need for more pointless stamps in my passport, especially one as farcical as a 'stamp-exempted stamp').

Everything is operationally confusing. That's what training is for. Either the agents are trained appropriately or they're not. If they can be trained to look for an e-Gate stamp in an Australian passport, they can be trained to know that e-Gate stamps don't exist for USA passports.

And again I'll repeat - I haven't had a problem recently with the BR check-in agents, and they can now handle everything at the check-in desks, so clearly the policies/procedures have been modified and they have been getting training.