First of all, you are ignoring the fact that there are sooooo many people who are so bad at math that they would have hard time doing additions, let alone anything else, I have seen people who failed in math multiple times, and never really understood it and didn't even really have any intend on getting any better neither.
So yeah, calculator calculates better than a human, faster and more precise, 99% of the population would fail getting the right answer, let alone be any faster, 99.9999% of the population would be either slower or wrong. Hence, yeah, I would say calculator is better, and with this regard, if done properly and used correctly, an AI trading bot could be better than 99.9999% of the traders as well.
No, I keep in mind that lots of people have problems with maths and I saw how many mistakes they made using calculator because they didn't understand how it works. If some tool is like a magic wand for a user they will make as many mistakes using it as it only possible. So if the one doesn't understand anything in trading and will rely on an AI they will lose anyway.
So no, calculator is not better, it is just faster. You can easily make a mistake as yourself as with a help of a tool, the only difference is that if you rely on a tool and trust it your mistake will probably happen more rare (statistically) and bring much bigger damage.