Jonathan Cooper, an animator for the game studio, recently tweeted out an in-house reason as to why Uncharted's Nathan Drake survives the way he does:
"Sidenote I learned on joining the team: Drake doesn't ever take bullet damage. The red UI that shows hits is to represent his luck running out. Eventually enemies will get a clear shot and kill him if he takes enough near-misses."
Gamers are heavily conditions to believe that when a noise happens and the screen starts to turn red, it means we are hurt. This is how it works in most games. So it's not unrealistic to make this assumption in everything we play. But this excuse offers a new way of looking at what "taking damage" means.
This legitimizes game logic, a polar opposite to games like Resident Evil. In that lore, one bite from a zombie means infection. Though the player can be bitten many times. This was passed off by the statement that gameplay is not canon.