Earlier quoted context omitted.
It's my understanding that a lot of US airports don't have an international-only terminal where people in transit wouldn't have to first go through customs & immigration. Quick google search brought me here: https://www.tripadvisor.com/ShowTopic-g1-i10702-k10297825-Do...
No airport does; you are required to clear the US border to connect. There's not such thing as a transit passenger in the US.
LHR-LAX-AKL requires all passengers to get off but those not terminating in LAX stay in a transit area (although there's still an immigration check).
And IAH supports international transit for bags, but you as a person still need to immigrate the normal way.