The user was not doing a normal transfer (at least, they didn't want to, but they ended up doing). They didn't know what they were doing at all, a simply Google search would have showed them the way. Using UIs instead of interacting with the contract directly would have prevented them from making the mistake they did. Doing a small test transfer before doing the big one would have revealed what was wrong as well.
It's not that I'm comparing writing software for moon missions with making cryptocurrency transactions. I was directly replying to mox1 implying that writing 100% correct code is impossible and shouldn't be attempted.