Yeah but a lot of this is because the US has a very self-centric world view, they think everyone is coming to visit them and have no concept at all of an international transfer. In particular they don't have real international departure lounges (that you can't just walk out of without going back thru immigration) like the rest of the world.

Anywhere else on the planet you would pass through a metal detector to get upstairs to the departure lounge and get on your plane.

This is why if you are travelling to Europe from NZ (as I will be on Monday) Singapore/Hong Kong/Shanghai/Tokyo are better candidates for transfers than LAX/SFO