I used to think that the reason why people say, "I don't like to talk about work" is because they're simply tired.
They want to unwind and decompress outside of the office.
But I've come to realize that there could be more reasons than that.
I personally don't like to talk about work or what I do because I tend to be ultra sensitive to criticism (under the disguise of feedback) and even well-meaning advice.
They all steer me off course when I think I "need" to at least give whatever it is they say a try. This usually ends up being a demoralizing task as I do not see the results I think I should be seeing. This can even wreck my mind for days to the point I am paralyzed into inaction.
And this is from good people who actually want the best for me. Imagine how aggravating it is then when a blowhard starts giving unsolicited advice in an arrogant manner.
So why don't I like to talk about work?
It's because I want to protect something dear to me.
So maybe, when you're trying to create small talk with someone you just met, you could talk about something else.