The approach of trains is always something to be aware of, so-called place of safety or not. Of course people shouldn't be near the platform edge, but many are, sometimes through no fault of their own in over-crowded conditions. People shouldn't do many things that they wouldn't if logic and order ruled the roost, but they do, which is why warnings are everywhere. It's why road vehicles now almost all have lights on during the day - a massive waste of energy, but supposedly necessary because the ante has been upped - once a few did it (Volvos and Saabs in the 1970s), others followed until we all have become conditioned to expect everything moving to be lit at all times. I'm not claiming that no safety improvement has occurred because of it, but pointing out that more and more warning is required as people become more and more expecting of it.