Had 2 totally different experiences at LAX.
First trip QF A380 Business Class 3rd out of plane door, 3 hours later just getting to front of line, angry little black lady screaming at everyone, move up, you go there etc etc. You would move up once every 5 minutes.
There were two Aussie diplomats in line with me and THEY didn't even get special lines and missed their connection. As we got to the front a white supervisor type lady asked what flight we were from, we told her, she said "But you landed 3 hours ago". She then started issuing orders in Spanish and suddenly the line started moving. Finally got through and then had to find my bags as they had all been moved somewhere else.
There was No customs hassle just waiting in line.
Next trip QF A380 Business again, same flight but months later, was bracing for the worst and literally the hall was deserted, again in first bunch off the plane, straight to immigration, easy through, collected bags and kerbside waiting for Hilton bus in 10 minutes.
Luck of the draw I think.