Another instance I recently noticed, and reacted moderately strongly against, was this post and its comments, where there is the implicit assumption that voting (for political candidates) is voluntary, and the discussion makes no consideration of compulsory voting.
The main reason I reacted against it was that the assumption was implicit, (mainly since nature of the discussion is not relevant to systems with compulsory voting).
But only 12 countries have enforced compulsory voting, out of ~150 democratic countries.
Recently, I have noticed a cultural bias for the United States running through LW threads. It is perhaps to be expected of an English-language website, but for one that is about, among other things, overcoming bias, it is important to recognize one's own.
Aspects of the bias I have observed include:
I'm not the first to raise such concerns, either.
By comparison, e.g. the English Wikipedia strikes me as an example of an international English-language project that's relatively successful at recognizing and fighting systemic bias, and a whole set of template messages to mark articles with identified problems.
To quote Wikipedia itself:
The reason I haven't mentioned other obvious biases, such as gender, age, education, or First World biases, is because those (in my experience) tend to be more subtle here on LW and because I'm myself subject to some of them. However, I might cook something up on them later.