Pop was an excellent Builder of the Old school and renowned for his quality craftsmanship. When his groups constructed a house, it was solid, square and built to last. Before I could follow in his steps, the credit squeeze of the 1960's hit, he shut up shop and we went farming, but I've always had an interest in developments in the building industry.

Standard structures are built with frames of timber or steel, and with materials not as plentiful as they were, framing timbers aren't the quality they once used to be.

I continue to have mates who are in the building game and one is a plasterboard fixer. Nowadays one of his best annoyances is making an attempt to hang plasterboard on frames that aren't square and which have warping in the timbers. If the essential structure isn't square and flat, the finishing off can't look as good as it should. He's regularly delayed in his work while the framers are called back to square up their work.
Consider also the time and material use in building the frames, erecting and finishing them, all adding to the price of his structure. Consider also the foundations of the normal structure, the numerous stumps to stabilize the floor, or the concrete slab. Then there's the vermin proofing, and rot proofing to contribute to the expenses.

Used shipping containers are built to hold cargos of twenty tons, across the oceans of the Earth, without distorting or corroding. They're built to definite measurements so they can be stacked on top of one another, loaded onto vans, trains and ships and precisely lock into place so they will not move in transit. They are constructed so that they can carry their 20-ton cargo supported by only the 4 corners of the container, without deforming and I repeat, they can be sacked on top of one another. They're sealed to be weather explanation and secure to stop break-in and burglary.
Naturally they've been utilized for storage sheds and offices on building sites for some considerable time now, because they are able to be simply moved without damaging them, they're engineered to be lifted and moved by cranes and forklifts. In places such as Papua New Guinea they're used as local shops due to the security they offer as thief-proof, thief explanation structures. They're built to be secure. Mining corporations have witnessed the advantages of using shipping boxes as housing for their workers at mine sites for a while as they can be fitted out at a workshop, carried to a mine site and quickly installed and inhabited.

Recently there's been some conversation that the utilization of shipping boxes as housing could be a useful alternative for housing the poor and homeless, but the feedback has been this will crate ghettos of unacceptable housing, making more issues than would be worked out.
I would suggest the humble shipping container represents the best revolution in the building industry for some considerable time. As other materials are becoming less available and the problems made public above endure and increase, shipping boxes, which have out-lived their original purpose, litter dockyards around the globe. They're ready to go housing modules, awaiting discovery and use. They're cheap components, more solid and durable than normal materials and techniques, which can often be erected quicker and more correctly than our current styles of housing.
When set on solid foundations, they're storm / hurricane explanation, would survive earthquakes and landslides better and can be employed either above or below ground level.

Naturally there are some restrictions. Modules predominately come in 8-foot widths and either ten or 40-foot lengths. Cutting them smaller would be compromise their design strength. They already come at standard ceiling height for housing. Nonetheless sidewalls can be opened up for broader living areas, but designs must be multiples of the standard dimensions of shipping boxes. And obviously, they seem like shipping boxes, unless, with some imagination, you clad them as you would any other kind of housing. And there'll be some building authorities for whom these are outside their capability to understand the advantages and approve.

Realistically the constraints are only our lack of imagination in exploiting these extraordinary basic components for safer, environmentally friendlier, less expensive shipping container housing. They've been licensed as housing structures and additions in varied authorities around the planet and any change takes some effort to cause. For those that can catch the vision, here is a chance waiting to be explored further.