I guess the first reason is that I was providing an answer to question about why would you want to use a container. My answer comes from personal experience in New Hampshire. I mention New Hampshire specifically because I do not know how general that situation for the rest of the US or other countries. However, it seems reasonable that they may be equivalent restrictions in other place, thus providing a reason for why a container may be desirable.
Secondly, the project is not being marketed for specifically for under-developed countries. In the linked article they do mention their experience in Kenya and that one of their target markets are governments to support development projects or refugee camps. But they also state that they are targeting individuals in the US. Also their website makes it clear that under-developed countries are not the major focus.