“His best guess for how the boxcar got turned into a home?”
Partly because there were no building codes back then. Otherwise it would have been prohibited.
Back then it was assumed that people had common sense.
A local realtor told me it is not completely unheard of to see a house in parts of Albuquerque that have a rammed earth floor, or adobe brick construction covered by a facade of plaster. People did what they could 100-130 years ago.
And they have remained that long because they are usually passed down within a family. So no inspections were done because there were no mortgages.
Folks in New Mexico are innovative when it comes to housing. In many places it’s a tough environment. Although Socorro County banned joining 2 singlewides with plywood and liquid nails a few years ago.