Why would a toddler be on a separate reservation?

AC owns and controls the system, so system failures are their responsibility.

Conceding that, in a very complex system, some glitches and unintended results are inevitable, that's what gate agents and flight crews are for: to provide sensible human intervention to resolve those glitches whenever possible. Not to pawn off their responsibilities on passengers, either out of laziness or out of a really unacceptable lack of knowledge of both regulation and policy.