Maybe it's state dependent? Which state are you in @MalloryCat?
Also, it may be due to incompetence of bank staff. They're maybe used to seeing DLs and IDs but not foreign passports. If that's the case, try speaking to other assstants, other branches or even other banks. There's so many online banks now out there too - Capital One, Discover, Amex, many more allowing you to open accounts / joint accounts without seeing a person.