1. At no point during the preparation of this meal did either of these women notice that there were no sweet potatoes. And apparently there were no sweet potatoes because sweet potatoes were not on the list. So what else would the person doing the shopping not pick up because it wasn't on a list? Or maybe she thought that it wasn't on the list because the other sister had already purchased sweet potatoes? Either way, the original point stands- why wasn't the lack of sweet potatoes noticed before this?
2. I note that all the meal prep was apparently done by these two women. The men here showed up to share in the consumption of this sweet potato-less feast, but had nothing to do with its creation. Because it's 2022 here in the real world but it will always be 1954 on television, I guess.