All the confusion from Americans is totally understandable. That being said, the title addressed his audience...Londoners. Comments suggesting a title change, so that people he wasn't intending to talk to can understand, is expecting too much. If the topic interests you, take the time to read for more context, maybe even ask, or research it.
You might want to explain to Americans that a "black cab driver" isn't what first comes to mind for them (especially as juxtaposed with "and I come in peace"). It might also be worth a mention what "Green Badge" means.