I really like writing the first draft of documentation. I get to run through the endpoints and even fine tune some of the details to fit to the big idea I'm creating about what the software does and how to use it best.
The problem comes months later when I'm in the weeds and a colleague asks a question. I try to fob them off to the documentation, but some details are out of date. I pray it's just one detail, and that I don't have to stop what I'm doing to rewrite the documentation now.
That's part of it. Plenty of working developers will also omit tests and documentation even without the feature-factory time pressure though. A lot of times, the need for technical documentation isn't even a blip on the TODO radar. If I had a dime for every README where the last change was "Initial commit" and the file only contained
Because those who control resources make a conscious decision to prioritize new features and/or bug fixes rather than documenting what exists already.