I don't understand. What would such a button have done?

If somebody needed help, the driver may very well have to decided to stop ASAP, at the same gore point, and the women could have then chosen to immediately get out, and one of them would have gotten killed. Literally nothing would have changed.

Indeed, it sounds like one of the women was shouting there was an emergency, so the driver stopped. That is effectively "I need help". What would your button do any differently?