In Sweden, bus stops have LCD (not LED) displays for upcoming services with a very dim backlight (fine at night, and in the day natural light makes them readable) which I believe are powered by solar power/rechargeable batteries - making them easy to install anywhere. I assume they also have an embedded SIM and even in remote areas, I am sure Vodafone or O2 has sufficient 2G coverage capable of sending tiny packets of data over GPRS or EDGE.
There's also an info button so you can press to hear the next services and the time, but no request to stop button presumably because of the likelihood of abuse.
I know we've trialled e-ink solutions on London bus stops in the UK but have no idea if it will ever roll out, and many new stops don't have any screens at all - presumably assuming everyone has an app to check. I think this is a step backwards, but maybe it's cost related - yet these LCD screens are probably very cheap.
I can't see any reason why such a system (that clearly already exists, but probably just needs different software) couldn't be used at quiet railway stations, and adapted so you could press a button that lights something up on the platform to alert the driver. They can also service to give train information and even for control to relay messages relating to delays etc.
A confirmation on the display can show the train is now stopping to provide assurance. For the amount of times the light would need to be on, having this powered by a solar charged battery would be more than sufficient.