Walking over an invisible arbitrary line at LAX in an underground walkway...
apparently meant that I had officially left the airport, and had to go around, and go through customs again. The little jobsworth cow who was guarding this invisible line could not handle the fact that there was no one else in the corridor, and there was nothing I could possibly hope to achieve by being a meter "outside" the airport that I couldn’t achieve had I not walked over this sodding line.

No - she was there to guard the line, and make sure no-one walked in the wrong way. Arguments that implied she could perhaps use some common sense, and let me walk the metre back into the airport were met with her fingers inching closer and closer to her walky talky.

Not wanting to upset the Americans and face the inevitability of being shot down in a hail of anti-terrorist gunfire, I grudgingly went off - outside the airport, and went through customs - again.

However - before I went through customs the first time I had eaten the remainder of my stash - and so by the second time I went through I had the mild green tinge of third degree paranoia to contend with while dozens of armed JULFs searched my bag for nail files, bottles of shampoo, lighters and other terrorist essentials.

Again.
(SigourneysBeaver took off and nuked the entire site from orbit on, Sat 29 Mar 2014, 7:19, 4 replies)

And by 'customs' you mean 'security'?
Otherwise, to go through customs again you'd have to re-enter the airport as a departing passenger, depart on an international flight, then return to the airport and go through the arrivals process again. All of which would not be allowed without a valid flight booking.
( Ghoti Fingers, Sat 29 Mar 2014, 12:45, closed)

Or you could follow the connecting flights directions.

( d.r._and_quinch when will you be famous?, Sat 29 Mar 2014, 15:06, closed)

Not in LAX, you still have to enter the country through passport control and customs, collect any luggage, then go and check your luggage in again for your onward flight.
'Merica's weird like that.
( Ghoti Fingers, Sat 29 Mar 2014, 17:51, closed)

It's not that weird when you think about it.
Many final destination airports do not have customs facilities. It sucks donkey balls doing all that at Atlanta though.
(Richy_T hundreds if not thousands of dollars, Mon 31 Mar 2014, 15:52, closed)