> I can't tell if this shows a terrible bias towards NA or if people who aren't from NA don't even bother applying for X reason(s) or get rejected.

Why not both?

There's a probably at least a bias to English fluency, if not a blanket rejection of non-English applications.

There's been a long-standing bias towards teams, which mandates a level of charisma and social skills that many talented engineers struggle with. For a long time, YC completely excluded solo founders.

And I believe being on-site is another requirement, which is classist. People from other states and countries who don't already have affluence probably don't even bother.