Is LAX different?
But it's not at all the way things work in US airports with international service.
The U.S. doesn't offer this, seemingly as a matter of policy, something which really annoys international travelers -- it's one of the most-complained-about U.S. policies on sites like FlyerTalk, even by U.S. citizens (because you can easily spend 1-2 hours clearing immigration, customs, and security for an international flight connection in the U.S. even if you didn't intend to visit the U.S. at all).
But as a result, almost all U.S. airports have some departing international and domestic passengers in the same terminal at the same time, or potentially allow both international and domestic departures from any terminal.
I think the specific option at LAX was post-2001, but you had to be on a specific pair of flights to take advantage of it. (I didn't do it, I just read about it on FlyerTalk and forgot the details.)
Yesterday I had a purely-domestic itinerary out of Philadelphia -- which is an international hub for US Airways/American Airlines -- and while waiting on my flight I wandered in and out of the international terminal several times without facing any additional security (I like watching the larger planes come and go, and the lounge in that terminal is nicer).
Which is the standard way international airports work in the US. There is no concept of "once you cross this point, you have to clear customs again to exit the terminal" here.