The fact of the matter is that literally every round in existence has failed to stop someone, somewhere, at some point in time, and while folks continue to use each and every instance of such an occurrence as a means to backup their cartridge of choice, the simple truth is that the world is an imperfect place, things seldom turn out the way that we expect them to, even with the most careful of planning, and frankly until someone literally invents a handheld weapon which is capable of completely disintegrating the target at the cellular/attomic level, there will never be a guaranteed one-shot-stop.

Honestly, this is coming from someone who isn't a fan of 9mm Luger too, in fact I feel that it's overrated, but realistically speaking, any shot that falls to result in incapacitation with a 9mm would be equally as ineffective with a .45 because ultimately shot placement is the single most decisive factor in a gunfight.
Seriously, if a 9mm misses a vital organ, then realistically speaking, a .45 might graze it at best, which isn't realistically going to make a difference in overall effectiveness.

Do I share the sentiment that all cartridges are somehow magically equal in terms of performance because there's no significant visible difference in a block of gel with no bones? Certainly not. Do I agree with the sentiment that 9mm is so close in performance to other duty cartridges that it makes no significant difference? I'm skeptical of that as well.
However, I have come to believe that ultimately Law Enforcement's decision to switch to 9mm Luger was a sound decision on the grounds that if you're going to outfit an equal opportunity workforce of officers with a single cartridge, then it's a good idea to pick one that virtually anyone can shoot effectively, costs less money, and will still be effective with proper shot placement.

9x19 Luger is an effective duty cartridge. Period. If you favor another cartridge and feel that it's more effective, then more power to you, carry is ultimately a personal choice, and there is no ideal one-size-fits-all cartridge for self-defense, and anyone who asserts otherwise in an arrogant fool. However, don't go cherry-picking cases in which a cartridge fails to stop someone as an example to back up your choice, especially not if an innocent was harmed/killed in the process, essentially using their hospital bed or coffin as a soapbox to promote your cartridge of choice. Have the guts to carry what you want regardless of what others think, because their feelings are irrelevant to your own personal choices and you shouldn't need their approval.

Personally, I've found that I love .40 S&W, a cartridge that folks by and large think isn't worth a darn, but I don't care, I just like it, and I carry it because I like it, the end. But guess what, 9mm works too, it can even work better for some. Sure, I wish that folks wouldn't be so obnoxiously insistent that it's a terrible cartridge which never had a valid reason to exist, and whatever they carry is always better for everyone on Earth including myself, but that's life, some people are just insecure jerks who need to have all of their life decisions validated by appealing to authority and putting down anyone who doesn't follow the same line of reasoning. Don't be like them. If you like .357 SIG (or whatever) then like it because you like it, don't go putting everyone else down or seeking validation. Okay? Good talk, carry on.

__________________
Shooting Comfort is bilateral.