That sauce will last for about 3 weeks so it isn’t a massive sugar dose!
Most of my meals are vegetarian and we always have fresh veg rather than frozen and we have one “less healthy” meal a week which can be veggie hotdog or burgers and fries. Not trying to justify anything but we do eat healthy most of the time.
I can understand why in the US though fast food is so popular with less well off families. We usually try and rent a place than stay in hotels as we find you waste so much time getting breakfast when all you want is some toast. Same for evening meals, still not that easy to get vegetarian meals in the US when chicken is considered to be vegetarian (we have encountered that). So we go and get fresh veg for our stay but the cost is often 3 or 4 times what we pay in Europe. There are obviously seasonal variations but fresh veg is very expensive over there. Even steak and fish in the US has increased. As a treat I would get a steak or some salmon but the cost of that jumped an awful lot too - about x4.
So when you can get a burger for $0.99 it is easy to see why junk food is popular.