It doesnt. If you know how. I personally reckon thats a major reason why folk go convenience. Cos anyone who can cook, knows the time difference between the two is miniscule. Microwave nothwithstanding. (And you cannot really cook a family meal in one).
If I CBA, I would happily show anyone who wants to know, how to cook tons of healthy meals for 2uppence. That is not a critique of folk who go convenience, far from it, My elderly Mum does, cos, "Why bother Mark?" Hard to argue with that.
Its not celebrity chef stuff, its being told the absolute basics, and from that, confidence grows.