Well, actually... There are. 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

Well, actually... There are. 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.