"I don't know what to make"

This is the seven o'clock question in its purest form, and I think it's the belief that does most of the work. Not "I can't", not "I'm too tired", but "I've got no idea", and the app has an idea, and so the app wins.

Look at when the question gets asked. Seven o'clock, hungry, standing in front of an open fridge. That's the worst possible moment to design a meal. Hunger narrows what you can think about, tiredness narrows it further, and an open fridge presents you with parts rather than dinners. Half a pepper isn't a dinner. Neither is a tin of tomatoes. Turning parts into a dinner is a small act of planning, and the one time of day you can't plan is the time you've chosen to try.

Pauline Ducrot and colleagues looked at meal planning in a large French cohort, over forty thousand adults, and found that people who planned their meals ahead, even just occasionally, had more varied diets and were more likely to meet their national guidelines, and among women were less likely to be overweight. That's a cross-sectional study and it can't say that planning causes any of it. But it's consistent with something anyone who cooks will tell you, which is that the deciding is the work, and the deciding is easy at a time when you're not hungry and impossible at a time when you are.

The people who cook on weeknights mostly don't know what to make at seven either. They knew at nine that morning, or on Sunday, or they don't need to know because there are six things they make and it's one of those. That's chapter 20, and the deciding at a better time is chapter 21. The point here is only that "I don't know what to make" is true and isn't a fact about you. It's a fact about seven o'clock. Ask the question at a different time and it has an answer.