I am a self-employed technical female as well but in my case I'm also a semi-recluse so my exposure to such things is greatly limited. Outside of being a developer I'm also known to occasionally fix my own cars and large appliances in lieu of taking them to be repaired.

In that context I have experienced similar issues but I chalk it up to people simply not being exposed enough to oddities like me. I am guilty of it too towards people I come across who break my mental image of how something "is."

For example, I live near Austin, Texas. I recently saw a really tall, very handsome black man wearing a cowboy hat and full-length duster. Certainly that's not the norm for me to see but not too incredibly odd either. That is until I heard him speak with the most refined British accent I'd ever heard in my life. I completely lost my composure and started viewing him if he were a novelty act. I have no doubt I was at least as much of an ass as the men you describe.

As other commenters have pondered, I wonder if these situations will actually start to decrease as the commonality of females in tech starts to increase.