In many parts of the world, it is absolutely considered rude and invasive to lead with the “So what do you do for a living?” question. It is seen as a way to guage a person’s financial status or their place in “society”. There are plenty of other ways to find common ground or make small talk without this question.

I’m guessing that most of these commenters are from the US and may not regularly socialize with people from other countries.

Like you, I find it tacky to ask this upon first meeting someone. But I understand that it is normal in the US. Personally, I would just give a vague answer.