I have seen other people do this so I know that I am not odd. We are not being pernickety, but we do load the conveyor in a general order of robustly packaged good first, fragile stuff last.
So why is it that check-out operators pick things up randomly? They will reach over things for the loose mushrooms followed by tins of beans, four bread rolls before a tin salmon and jar of jam.........grrrrr.
The next time I am asked: "Would you like help with your packing?" I will reply, "If you go all random on me with stuff on the conveyor belt, then yes!"