i have actually never lost a deer bowhunting, but I have lost three shotgun hunting. The reason I lost three with a shotgun is because I assumed gun hunting was "easy" and I did not put in the time practicing with my slug gun like I did with my bow. My bow on the other hand I spent hours practicing with and have had very good luck, seldomly having an animal go more than 70 yards. I dont think the weapon is blame for lost deer, it is a matter of the hunter proficiency with the weapon and the choices he/she makes.
I also have set rules for taking a bow shot
1. nothing quartering to me at all, ever.
2. nothing quartering away at more than a 45 degree angle
3. nothing over 30 yards.
I think if more people followed those guides there wouldnt be many lost bow shot deer.