Do you actually think that a shipping container can't be made suitable and legal for habitation??
Then can you explain these?
I've seen some awesome articles about using shipping containers for housing. In Europe, Asia and other areas they are used to build entire apartment complexes. It's not that hard to cut out holes for windows and doors, string electrical wiring and mount plumbing pipes inside, then finish the walls/ceilings/floors to look like a stick-built home. You'd have to take some extra measures in a tropical and storm-prone climate like PR -- anchoring them to the ground, and rust-protection.
https://www.containerhomeplans.org/...n-before-building-my-shipping-container-home/
