So is it customary to tip the person doing the bagging? Or maybe a designated bagger will do it faster, resulting in less wait times?
My favourite system is where I place my cart next to another one, and the cashier will scan everything while placing the item in the other cart, where I could have placed boxes if I wanted to.
It’s the same for filling your car with petrol.
But how does this person provide any value though? That person has to be paid as well, and doing something a customer can do well by themselves provides very little value. It used to be necessary, older petrol pumps had to be manually enabled or had no stop valve that person is required. With modern pumps having a person fill up your car is equally unnecessary.