Funny, in my variety of Asian ethnic heritage, as a rule, we do not cook with ready-made items...for our ethnic dishes. However, I noticed that there is a dish or two that when using American items, incorporate canned meats, like Spam or corned beef (I was an adult before I learned that corned beef didn't normally come in a can). I'm pretty sure the reason for the canned meats comes from wartime though.
As far as using ready-made items regularly in American recipes, I think it might be a cultural thing and while I was born and raised in the US, so I'm very much American, among the people I know, we don't, for the most part, cook with ready-made items or rely on already prepared foods for our meals. The recipes I see don't rely on these items either (a colleague of DF's, knowing how much I love to cook and bake, actually, unsolicited, sent him some recipes to send to me, thinking they were great, and they were atrocious-looking to me and did, mostly, rely on opening cans of stuff here and there in order to "cook" -- I did let him know there was no way I was making these things as they didn't even sound tasty to me).
Anyway, when I was a young child with my mother in the grocery store, I asked her why she didn't buy frozen dinners like we saw advertised so much on the TV. She said, "Those are for lazy people." That's always stuck in my head, and I thought she was just being really judgmental. However, now, I realize she wanted to make sure we had healthy diets and didn't rely on pre-made and/or processed foods.