It's difficult or impossible for dual parent households working 2-3 minimum wage jobs each to have time to plant a garden or do anything else but drop dead asleep every 18 hours only to do it all over again the following day.
Idk about 2-3 minimum wage job. Are people in the US really doing that?
But I grew up in a place where having a garden is pretty natural. It's something you take care of between putting the trash out and walking the dogs. It does not have to be amazing magazine-ready.
But having a staple of stuff that grew easily and are forgetful. ( Courges, Carots, potatoes, aromatic plants .. )
Yes, they absolutely are doing that. Life in the US is a worsening hellscape for the increasingly permanent underclass, commonly one small medical crisis away from homelessness. A "managed population", most reliably vote to make it worse for themselves, year after year.
Just controlling ground for a garden is a privilege.
People who are healthier and wealthier find it easier to have a garden.
It is possible that gardening is good for your health, but teasing apart how much of which causes which would not be easy.