I don't understand

Today I was in line waiting to check out at Target. There was a family behind me; mom, dad, a toddler in the cart and a baby that dad was holding. It was dinner time and the toddler was whining to be picked up out of the cart. Mom just kept telling him no and telling him that he could not be held. She was short with the child, it seemed as though she expected this two year old little boy to be able to handle waiting for dinner and to understand that the baby had to be held but that he could not get his needs met. Between telling the little boy no every time he asked to get out of the cart, she told dad that the child was probably hungry and why didn't he understand that he had to wait. I was a bit taken aback. I held my tongue and did not intervene. I wanted so badly to turn around and tell this mom that shopping with two children under age three and expecting them to understand that they had to wait to eat was just plain mean. Why don't people realize that toddlers don't have the patience or stamina to wait for meals, or to sit in a cart for over an hour! Ugh.