[Balanor]

ICly the explanation is that the Spectral Red Wizard cannot return you to a location that has theoretically moved from where your death occurred (cannot go back to the wagon), for instance. This is one of the hazards of taking a caravan rather than going overland by foot or by horse - however even death during overland travel can lead to a loss of all your equipment if you don't return quickly enough (bandits, roaming monsters, whatever finds and takes it)

OOCly, the logistics of handling death on caravans, ships, and even in overland areas is very tricky. At this time perhaps the 'easy way out' has been taken by not dealing with all the various situations that can arise if a dead PC tries to get back to a moving target. So PCs, if killed during transit somewhere, can not go back to the location of their death in those situations. This may get addressed in the future, but as it is hopefully an uncommon occurrence (death by assassin or another PC is about all I can think of that would cause this...?), those unlucky enough to die on a wagon or ship will need to either rely on others to get their stuff or else get some money from their vaults and try to get on the same ship/caravan again.