Containers aren't cheaper than a modular (manufactured) home, they are just trendier. That's why you haven't seen containers replacing manufactured homes in trailer parks.
This is kind of like the tiny house movement. It's not actually cheaper than existing options, but it is disassociated with the "white trash" connotation from living in a mobile home. Rich people will pay extra to not look poor.
Tragically, it looks as though actually the majority of household expenditure in the USA is to not look poor. Well, if not, we certainly don't know what it is for: it isn't making us any happier.
Status, not wealth, is linked to happiness.
Better put: "Spending money you don't have for things you don't need to impress people you don't like."
This is kind of like the tiny house movement. It's not actually cheaper than existing options, but it is disassociated with the "white trash" connotation from living in a mobile home. Rich people will pay extra to not look poor.