They have been specifically manufactured as modular, prefabricated homes because building codes prevent the developer from using recycled containers.
Which is about 5k of the cost. And a prime example of the stupidity of government regulations.
Hardly. Shipping containers have no windows, electricity or plumbing, and hence are not constructed with ventilation or the need for electricity, water or sewage connections. The "stupid government regulations" you're talking about require that all construction for human habitation be properly equipped for ventilation and ability to connect with public utilities.
The conservative assumption that all government regulation is bad, once again fails to realize how many people are bilked into paying money for something that isn't very good for them at all, just because it's cheaper. It would be far cheaper to actually build something that is designed for human habitation that it would be to take apart a old metal container and cut windows and doorways into the shell, and retrofit it for water, electricity and sewage. Humans don't live in metal sheds, nor should they.
But again, the problem isn't government investment in housing, it's government hiring large corporations to solve the problem. Giving a corporation $600,000 to build a house for a family is ridiculous. You could give $100,000 to 6 families, and let them build their own houses with the funds.
The US government keeps throwing money at corporations and asking them to solve problems. It's not working. At the same time, they decry giving money to low income people.
In Canada, we give money to low income people and let them spend it in the marketplace. Low income parents get a "child tax benefit" of up to $5000 per year per child, for families with income of less than $72,000. This isn't a program where the government gives billions to the day-care industry and asks them to create day care spaces. They wiould spend millions on fancy new facilities at a cost of thousands of dollars per space. This is a benefit where they give poor working parents money for day-care, and the private industry completes to fill the demand the money helps create.
Giving the money to the people and letting them buy the house, will encourage the builders to build homes these people can afford, with their grants. And the cost per unit will come down drastically.