But you don't factor in time and shelf life. Is your time worthless to you? If you factor in your time as worth $20/hour, a prepared meal pays off fast. Furthermore, fresh fruits and vegetables go bad fast and have to be replenished by more frequent trips to the grocery store, which takes more time and gas.
And before you counter with this woman's example, of course she had plenty of time to cook, but you argued that healthy food is not more expensive. Well, guess what, it is:
The healthier market basket was always significantly more expensive than the TFP market basket (Table 3). The average cost of the TFP is $194 for 2 weeks, and the cost of the healthier basket is $230. The average increase in cost was $36 and ranged from $32 to $41 depending on store location or store type. The healthier market basket was between 17% and 19% higher than the TFP in Sacramento, and between 18% and 22% higher in Los Angeles.Source.
I think it can be more time consuming, but it also can be simple.
Scooping out some yogurt with a sliced banana takes 2 minutes.
Cooking some oatmeal takes 5 minutes
Scrambling some eggs with some sliced tomatoes takes 5 minutes.
Toasting a piece of whole wheat bread and putting low fat cream cheese on it takes 3 minutes.
Washing and peeling a carrot takes one minute.
Etc.