Well that brings me back to my original question (which you did not answer).

Do you think if people consistently referred to a group of people that included you as "hey girls" you would find it....a bit strange?

It's quite ordinary. Particularly in all male contexts where it isn't ambiguous, like construction or sports. Also "ladies". Metonymy is weird like that.

In contexts like construction or sports referring to an all male group as "girls" or "ladies" is derisive or, at the very least, sarcastic. It's interesting to consider the implications of that.

Have you noticed a strange pattern when people talk. When someone refer to people they don't know they tend to default to their own gender, unless there is a cultural clue, in which they then default to that clue.

I find it a interesting quirk of human behavior. It not very noticeable unless you listen for it, but once you do, it is a very noticeable during a conference with a high rate of speakers that do not share your own gender.

It implies that they particularly value predominantly masculine virtues in their work, like physical strength and aggression. Which is sometimes reasonable and sometimes not.