There are two kinds of reliability:

Machine reliability does the same thing the same way every time. If there's an error on some input, it will always make that error on that input, and somebody can investigate it and fix it, and then it will never make that error again.

Human reliability does the job even when there are weird variances or things nobody bothered to check for. If the printer runs out of paper, the human goes to the supply cabinet and gets out paper and if there is no paper the human decides whether to run out right now and buy more paper or postpone the print job until tomorrow; possibly they decide that the printing doesn't need to be done at all, or they go downstairs and use a different printer... Humans make errors but they fix them.

LLMs are not machine reliable and not human reliable.

> . If the printer runs out of paper, the human goes to the supply cabinet and gets out paper and if there is no paper the human decides

Sure, these humans exists, but the others, that I happen to encounter every day unfortunately, are the ones that go into broken mode immediately when something is unexpected. Today I ordered something they ran out of and the girl behind the counter just stared in The Deep not having a clue what to do now. Do or say. Or yesterday at dinner, the PoS (on batteries) ran out of power when I tried to pay for dinner. The guy just walked off and went outside for a smoke. I stood there with waiting to pay. The owner apologized and fixed it after a while but I am saying, the employee who runs out of paper and then finds and puts more paper in is not very ... common... In the real world.

Or the human might take the printer out back with his buddies and smash it to bits ;)