Problem with shipping containers is that they should be decontaminated and sanded down prior to living use - the contents get gassed, leak out dangerous stuff and old insulation materials may prove dangerous, same for the paint.
It never is. That's why all camp stoves come with a warning not to cook in enclosed spaces. Just a few weeks ago I was out camping and a father/son duo died in their tent because it was raining out and they wanted to use the stove to warm up food.
These shipping containers are converted. The idea isn't to just take a shipping container and start living there. You convert it so it is safe to live in it.
