[lrpe]

Is that really something people do? Really seems insincere and inappropriate to me. Is it a cultural thing?

[Supermancho]

Over 25 years as a programmer, I've only seen some very jr developers (no industry experience), do this. It's unlikely to help you in getting the position, which is why it's rare.

[iteria]

Some nearly 15 years ago, one of my elders told me to do this. I was later told this was the reason they picked me over someone else. That's the story of how I got a job at a megacorp. In massive companies, HR people can feel really undervalued. In a sea of a dozen of equally qualified juniors, a hand written card can tip the scale. At least then. It wouldn't have moved me and I don't know when the last time an HR person got to be the final decision maker on a hire, but that's some context.

[specproc]

American possibly. I've only seen them from American candidates.

[ghaff]

Maybe? It just seems like good manners. Don't overdo it but as an interviewer I don't expect an email but I'd find it very normal to receive a short polite one.