Originally Posted by
HkCaGu
Because if a kiosk or computer is not expecting you, it will kick you to a human or it will take longer.
That is not the case for US-EU/Schengen/Canadian dual-nationals using their non-US nationality passports at non-US ports of entry where they have the non-US passport being scanned at the counters/kiosks on arrival in their country/region of citizenship.
Even for dual US-UK citizen passport users, using the UK citizen passport — BNO passport users don’t have the same UK entry allowance as UK citizens — at UK egates works just fine even when having flown into the UK with only the US passport and US passport details presented to the airline flying ORD/IAD/JFK/MSP/EWR/BOS/DFW/ATL/MIA/CLT/IAH-LHR.
It works just fine for my US dual-citizen travel party members as is.