I’m thinking that with soil additions and reworking, lawns could become healthy, productive veggie gardens again. The soil additions are necessary because the builders brought a lot of subsoil to the surface digging basements.
No argument there. In our old house the topsoil was awful.
One problem is all the homeowners associations that would put a lien on your house if they saw a tomato plant in the front yard. Some even in the backyard as well.
In a SHTF scenario they might change their minds. The problems then become complete lack of vegetable gardening know how and no seeds or plants available just then.
Biggest problem is probably not 1 in 100 people in those neighborhoods have any clue about growing veggies. And it’s generationally removed at this point too. That area has been relatively wealthy long enough that even their grandparents likely didn’t grow veggies. There are exceptions.