Another major factor that the WHO neglects to mention is the everyday stress that people from low-middle income regions suffer from.
The constant anxiety about where your next meal will come from or how you will pay for housing, gas for your vehicle and many other stressful bills can be quite distracting. As I mentioned earlier, when I got into my car accident I was very stressed out, mainly from the lack of sleep and the long work hours that I kept. I’d basically spend my entire day at work - sometimes 10+ hours a day, not including travel time. After a while, this wears on you mentally and the drive to and from work becomes more and more difficult. Not because the route is challenging or filled with obstacles, but rather because I was generally in a groggy, cranky, and resentful state of mind and I had to force myself to show up at a job that I hated.
Those that work much longer hours in extreme and harsh conditions, traveling longer distances to and from work on unsafe routes, for far less pay with large families to care for must be under a tremendous amount of stress. That level of stress is very distracting and it will totally impair your judgement and make for really unsafe conditions on the roads; especially if the majority of the drivers on the roads are operating vehicles under these conditions.
Many travelers in poor countries risk their lives to transport themselves and cargo in dangerous conditions.