by Rad80
Here's a thematic justification: it's not about you, it's about the CIA (And Soviet) infrastructure.* The CIA will grant you free flights to allied cities, so you still fly for free with any alias.
* You do not fly to Soviet airports, because they'd track you. Even a Soviet alias is a fake identity: a border check might burn it right away.
* In neutral cities you pay the ticket like everyone else, but are not especially fearful of checks.