Hi Mark,
is it a normal part of the manufacturing process? Yes, it is seam sealer, made to cover and seal areas where panels have been welded or overlapped, the purpose is to prevent moisture getting in between panels and prevent rusting.
seam sealer should last the lifetime of the vehicle.
That is not to say the application could be a lot better, but that is slightly subjective, although given the the context of a high cost Camper I think there is massive room for improvement and finesse.
Unfortunately there is little you can do by way of remedial work to practically and effectively improve the exiting look and finish without major remedial works which would involve full removal of the painted sealer and surrounding area back to bare metal (albeit galvanised) them re prep and reapply sealer, re- paint all affected areas, which would be the whole side of the van, obviously this would not be practical, and could be counter productive due to being extremely labour intensive, invasive and potential extensive Repaint