None of those items, if made at home, would require sugar. So how come it's put in the processed versions? The only thing I can think of is that the sweet taste camouflages what would otherwise be a bland recipe.
This is my non-scientific observation, and as far as all of the technical stuff, I will leave it to people who know what they are talking about. I don't.
HFCS is pretty much used as a sugar replacer. Where there was once sugar, or would be sugar, there is now HFCS. They normally use equal amounts since the sweetness is almost identical to that of sugar. The primary reason this substitution is being made is because we have to pay so much more for sugar in this country than the rest of the world. Thank the protectionists who cost us more than $2.5 billion a year on sugar alone. Some other products use HFCS because it provides a better texture (more chewy) and helps to retain moisture. It also mixes much better than sugar and resists breaking down better than sugar.
I have seen it as an ingredient in hot dogs, spaghetti sauce, chicken pot pies, and salad dressings.
I think most of your examples contain corn syrup rather than HFCS. Corn syrup is mostly glucose and is not as sweet as HFCS. Americans like their foods, hot dogs, pot pies and spag sauce included, with a little sweetness. Corn syrup also helps to maintain moistness and freshness. They may also use this to create a "flavor" without having to add more expensive seasonings. Mostly though, it's used to add a little sweetness to products because that's what American consumers prefer.