Since there are less women in tech, technical people assume they are boring most people with technical jargon including most women (probabilistically). I bet if you dropped some technical info early it would knock it out of that mode quickly. I know when a women knows or doesn't know about tech I do change how I talk but I do this with anyone that is technical/non-technical. The old Feynman tune it to your crowd when you educate/market type of steward.
Also since there are so few women in tech, men don't usually work with them during the day and aren't the most alpha, lots of them could be shy or even have difficulty with eye contact at all. If they are introverted even moreso like many programmers are. Many are also young and not married which leads to awkwardness at times with ladies.
I think there are lots of opportunities for really skilled women but these intricacies should be stated more often so people understand and correct their assumptions. People need examples like this to learn how subtle it can be because just hearing 'sexism' doesn't help educate, more women with more examples as it is eye opening and helps understanding of this problem.