 Why doesn't Ninian know much about meals?
Nobody in the neighborhood was surprised when Martin's mother disappeared and Ninian came to take care of him. "He's dissatisfied with the current social order and killing you is part of an elaborate plan he's formulated to change it. But Ninian didn't know that and she went into a real tizzy, babbling that Martin had been sick and would make up the work. There were hot water and heat all the time and a freezer well stocked with food—somewhat erratically chosen, for Ninian didn't know much about meals. And, on those worlds, it's far cheaper to use native labor than to ship out all that expensive machinery.
 Ninian is used to having servants plan and serve her meals. She's never had to buy food herself.
 In the future, all the nutrients a human needs come in an easy-to-swallow capsule.  In the future, they don't eat meals.  Ninian is not a chef.  Ninian is used to having servants plan and serve her meals. She's never had to buy food herself.