Originally Posted by
joejones
Most countries that I have visited by air (off the top of my head: UK, Ireland, Japan, China, Taiwan, Korea, Germany, France, Italy) segregate international departures from domestic departures.
The US is weird in that it has no immigration exit control: that function is handled by the carrier rather than by immigration agents. The US also has no concept of sterile transit from one international flight directly to another.
These are the main reasons the flows vary so much between the USA and other places.
I don't mind the US's lack of exit controls but I positively despise the lack of transit. It is a moronic policy that provides no benefits to the country but does a great job of annoying potential travelers and costing the airlines money in the form of lost business and costs passengers money in the form of unnecessary visas.