Originally Posted by
javabytes
An awful analogy, and in fact the complete opposite of OP's circumstances. In your example, the passenger has created additional evidence that directly contradicts their desired travel plans (in this case, a ticketed reservation that includes travel from B to C which they have no intention of taking.) In OP's scenario, the tickets reflect the actual planned itinerary.
You're missing the point. The ticketed destination is what matters.
The fact JNB airport is setup is such a way to allow a passenger to skip immigration is irrelevant. The passenger was ticketed to JNB and therefore needed documents to enter ZA. The fact that South African airways allowed them to checkin airside is irrelevant. They were starting anew at JNB and thus needed to meet entry requirements even if they had no intention of entering ZA.
OP met transit requirements, however wasn't a transit passenger. AFAIK no where in ZA law does it say that a passenger on two different tickets qualifies to be a transit passenger. Absent that OP was an arriving passenger and needed to have documents to enter the country. The fact that could skip it at JNB is simply a side effect of how the airport is setup.