In 1971, Gerald M Weinberg wrote one of the classic books on software development and its management. Weinberg was one of the first to emphasize the importance of social psychology in software development, and his analysis laid a foundation for all who came after.

In a section of chapter 4 named "Error and Ego", Weinstein observed that the programmers of his time tended toward a "detached" personality type that prefers to be "alone and creative." That's not a bad thing in itself, but Weinstein pointed out that their detachment from other people often led to an over-attachment to the programs they created.

When programmers are overly attached to their programs, and testing reveals bugs in those programs, programmers are all too likely to regard those bugs as negative judgements on themselves as well as the products of their work. People don't like to be judged negatively, so they try not to do things that lead to those negative judgements. Programmers are people too, so programmers will try not to find bugs in their programs.

That's only human, but it's counter-productive.