Originally Posted by
bensyd
Huh?
The purpose of a passport is to identify nationality.
I think
number_6 may have been referring to the case of dual nationality?
An airline can ask for proof of entitlement to stay at a destination if it's not immediately apparent the passenger has a right to enter and stay at the destination (without a return ticket/visa etc)
As to the OP - more info would be helpful as a data point.