One of the main reasons why shipping containers are superior in terms of cost is because they are readily available and relatively cheap. Containers are used to transport goods all over the world, and due to the imbalance of trade, many shipping companies are left with surplus containers that they sell off at a discounted price. Additionally, the cost of converting a shipping container into a building structure is relatively low compared to traditional construction methods. This is because containers are designed to be stackable and modular, which makes them easy to transport and assemble. 

Shipping containers are also superior in terms of sustainability. In many cases, these containers are repurposed instead of being sent to a landfill, which reduces the amount of waste generated by the construction industry.