Nah, if they stormed out right after you told them the salary, it's pretty obvious.

It sounds more like an example of 'cultural density' -- not wanting to realize or acknowledge something that's at odds with what your local culture desires (in this case, the desire to pay as little as possible).

This was the highest paid position in the company (30k a year) and a salary (which only their managers were paid in a salary). They thought they were offering a really good salary, not realizing it was FAR below market rate. They still hired engineers at below market rate (~60k) but I helped them find some really smart junior engineers who could maintain the existing code; and warned them that these engineers would likely leave in the next year or two, max.

They were able to become fairly profitable with full-time engineers, eventually, and ended up paying above market rate, last I heard.

What? Was everyone else at the company living in their car and relying on the food bank to feed themselves? Or was this in some strange ultra-low-CoL environment?

It was long ago, maybe 2009ish? Developer salaries were actually going down, IIRC, during this time. Likely due to companies exactly like this one and pivoting to more digital solutions. 100+k was very rare outside of SV. Adjusted for inflation, 30k is roughly equal to about 40-50k in todays dollars.