Where did you get the 2.8 million figure? Wikipedia says "an estimated 303,000 women killed each year in childbirth and pregnancy worldwide", which isn't the same.
I'd guess the stats favour non-hospital births because they are only done when deemed safe beforehand. No midwife will let you do it outside hospital if they spotted anything wrong.
It's wild that on a site that educated people use that you're seeing people advocate for homebirths. I'm guessing that next to nobody on hacker news have seen a delivery go south and need an emergency C-section. If you're at home, the ambulance is going to be way too late to prevent serious harm to the baby (hypoxic brain injury) or the mom (hemorrhage, hypotensive shock). There's a reason why OB/Gyns don't have their babies at home - it's because they have seen it go wrong.
https://en.wikipedia.org/wiki/Maternal_death