Strange. In the US, I don't know any Brits or Aussies, but I hear the term brekkie all the time, as far back as I can remember. It's simply a shortcut word for breakfast like spendy is a shortcut for expensive. Or any of dozens of other examples. Lorry and bonnet are not shortcut words, and would definitely turn my head. Anyway, back on topic, I'm positive I've had burgers early AM at McDs in US airports, though it has been several years.