My mom was a single mom so I know exactly what you mean, A. Nonymous, however health was non-negotiable and always a concern. As a civil servant, she never earned much either and regularly had to work extra hours because people were off sick etc… She sometimes worked Saturdays, too.
And yet, our home was always spotless and our dinners were as healthy as could be under the circumstances. Good food needn’t take much time, it’s a matter of ingredients, planning, and skill / knowledge, which anyone can acquire with a little curiosity.
I learned to cook as a kid, I also learned how to use a washing machine, and I was always expected to help with the housework. Division of labor works wonders in families and teaches kids to be responsible from a young age. My friend in OH has done this too with her two kids, so it does happen in the US as well.
I believe the difference between our two continents is deeply cultural. Despite the governmental help available to the poorest, many French families still struggle to buy food. In the town where my mother lives, there are women and children who gather every night at the railway station and good samaritans who bring them hot dinners because even our social safety net fails and social services and soup kitchens struggle. So it is regular people who often don’t have much who take it upon themselves to help out those who have even less than them.
Because if you’ve made enough food for four for example, you can always serve slightly smaller portions and feed an extra person or even two.