Part of the issue is that engineers believe they are perfectly rational creatures with no feelings. What this actually means is that they are unaware of their feelings and so their feelings control them without them knowing it.
Engineers can rarely see their own sexism precisely because, as a group, they lack self-knowledge and emotional intelligence.
Groups that lack emotional intelligence are always the most oblivious to their own prejudice. Outsiders consider it obvious that engineers are sexist. Engineers themselves are oblivious.
On top of that, engineers in general tend to have really inflated self-images. Many engineers just flat out think they are better than non-technical people. This arrogance means they are unwilling to accept criticism from non-engineers. Usually they deflect the criticism by claiming the person has no evidence or is making logical errors. What the engineer is really doing is missing the forest for the trees, being overly literal, failing to see things from the eyes of others, and demanding perfect evidence in situations where perfect evidence is unreasonable and unattainable.
Engineers can rarely see their own sexism precisely because, as a group, they lack self-knowledge and emotional intelligence.
Groups that lack emotional intelligence are always the most oblivious to their own prejudice. Outsiders consider it obvious that engineers are sexist. Engineers themselves are oblivious.
On top of that, engineers in general tend to have really inflated self-images. Many engineers just flat out think they are better than non-technical people. This arrogance means they are unwilling to accept criticism from non-engineers. Usually they deflect the criticism by claiming the person has no evidence or is making logical errors. What the engineer is really doing is missing the forest for the trees, being overly literal, failing to see things from the eyes of others, and demanding perfect evidence in situations where perfect evidence is unreasonable and unattainable.