There is actually a good reason to not talk about good practices in those books.
The book is intended to be read by psychologists. Try to talk to a psychologist (or any other person who doesn't care at all about software development) about OOP, about how to indent code properly and about version control, this person will stop listening to you in a few minutes.
It's like in The Big Bang Theory, Series 3 Episode 5, when Howard asks Bernadette if she likes computers, and she answers: "I use them. I don't like them".
People who use computers want their work to be done, with some help from a computer, but they don't want spending their time learning how computers work, how real, professional software development is done, etc. They are not geeks. They are users.
That's why books oriented to specific non-geek audience are better when they tell little or nothing about best practices. It can feel strange for us, who have years of professional experience and who think that it is impossible to work for a company where there are no source control. But that's why those books are not for us, nor must they be read by us.
There are lots of publications about the low quality of source code written by scientists. The problem they found is that published code must be easily verifiable by other scientists in order to be able to verify what is said in the publication.
Finally, I think best practices must be enforced for people who are not geeks, but who write software daily. This is a case of most scientists. But this is only the case of some psychologists; most of them will never write programs, or, at least, not very often, and would never care about source control or other stuff like that. For those who will actually dedicate their career to the development of applications related to psychology, I hope they may be a bit more interested in professional software development, and will read general development books which promote best practices.