I guided for years on a bow only ranch. It didn’t take long for the owner to ban mechanical heads. Not a problem on most shots on deer. On hogs, we spent many countless hours tracking unrecovered hogs.
I would chalk that up to a combination of poor shot placement and ill-suited tackle. Pigs are tough but not invincible.
People always jump straight to the broadhead as the absolute problem and don't pay attention to arrow weight, speed, or poundage.
For years I shot the rocket sidewinder. In penetration tests they performed as well as most fixed broadheads. they got beat by some 2 blade cut on contact 1 piece muzzy by 1/2 "....that was the only one that beat it. But the Rocket had way more cutting diameter and a 3rd blade.
Fixed blade heads are fine.....and work for many...but that doesent mean mechanicals don't work.
IME the vast majority of folks losing deer with mechanicals don't have the proper set up, can't shoot or both and would be losing deer regardless of arrow head design.
I have personally shot 2 deer that I know I would not have recovered due to my poor shot placement if I had not been shooting large diameter expendables. The worst shot deer dropped within 60 yards and the other went just over 100.