Buffybr, I totally misread that- when you said of 36 animals you shot with the Barnes, you only recovered 6 I thought you were talking about the animals!! I was going to suggest that perhaps bullets aren't the problem.
Anyway, that is exactly my experience with the TTSX. Occasionally a bullet is found, but usually a pass through. Exactly what I want.
And although I am a big fan of the TTSX, I in some ways agree with the OP and in some ways disagree. I agree that a bullet that worked 100 years ago will still work as well: animals haven't upgraded their armor. On the other hand, in the past, quotas were larger, duration of hunts was longer, and in the days before telescopic sights were common, a lot of animals at range were written off as a miss when in fact they were wounded.
A premium bullet is by no means necessary. It does open the envelope up for success. A 30-06 on impala standing broadside doesn't require and probably doesn't benefit from a premium bullet. On the other hand, a 243 (where legal, etc, etc) with a TTSX will cleanly kill a zebra.
In my opinion, (and frankly only moderate experience involving perhaps 20-30 animals) the notorious toughness of African animals as it regards plains game is a myth perpetuated to protect the ego of paying customers. I have no first-hand experience regards dangerous game. Yes, a 2000 pound eland is going to take more punishment than a whitetail deer, but I'm not convinced it will take pound for pound significantly more punishment. A bullet through the vitals will kill it, period. It will take longer to bleed to death from a small hole than a smaller animal will. The only toughness I've seen on African game relates directly to it being tough to kill an animal quickly with a bullet in its ass or guts. Hit something important and African animals die the same as any others.