But you still have to build additional safeties into the craft if it's rated for humans. A refueling craft is more complex than a non refueling craft. A crewed

But you still have to build additional safeties into the craft if it's rated for humans. A refueling craft is more complex than a non refueling craft. A crewed craft is more complex than an uncrewed craft (even if no one is aboard). A crewed, refueling craft is more complex still.