Why is close assault so deadly to passengers?

[Imp]

Not really, if its open top they are vulnerable or if they tried defending it through gun slits or a hatch. The passenger section could have been penetrated, game terms a round from say one of the squads GL launchers would make a nice mess of the insides while leaving the chassis & hence mobility intact, does not show an * as does not effect AFVs capabilities. Or of course you can assume the passengers tried to disembark to defend it & got cut down in the process.