The problem is that you don't know which 5% are wrong. The AI is confidently wrong all the time. So the only way to be sure is to double check everything, and at some point its easier to just do it the right way.
Sure, some things don't need to be perfect. But how much do you really want to risk? This company thought a little bit of potential misinformation was acceptable, and so it caused a completely self inflicted PR scandal, pissed off their customer base, and lost them a lot of confidence and revenue. Was that 5% error worth it?
Stories like this are going to keep coming the more we rely on AI to do things humans should be doing.
Someday you'll be affected by the fallout of some system failing because you happen to wind up in the 5% failure gap that some manager thought was acceptable (if that manager even ran a calculation and didn't just blindly trust whatever some other AI system told them) I just hope it's something as trivial as an IDE and not something in your car, your bank, or your hospital. But certainly LLMs will be irresponsibly shoved into all three within the next few years, if it's not there already.