I think you have it backwards. The addition fails hardest when things are independent - which is true of most millimort risks in these tables. Smoking a cigaret

I think you have it backwards. The addition fails hardest when things are independent - which is true of most millimort risks in these tables. Smoking a cigarette and riding a motorcycle are totally uncorrelated in terms of how they cause death, so adding their millimorts naively won’t work at all.