1. The graphical injuries shown are an admission by the railway company that such injuries can happen, increasing its liability when something does.
2. The graphical nature of the posters could "trigger" traumatic experiences in someone...
Note that these are from the mid 1960s - there is technology today to design out some of those hazards that didn't exist then. Platform screen doors for example didn't exist back then, but because they do now you can no longer warn about someone getting to close to the platform edge, you need to design it out by adding those doors (such doors do not work on curved platforms so signs are still useful for some really old stations that are impossible to remodel). For all the others you have a good case against the railroad if you get hit by a train since they should have doors, fences, and quad arm crossing guards which by design make it nearly impossible to get on the track and thus there is no danger of getting hit.
They also don't work if you've got multiple types of rolling stock with incompatible door layouts, and ideally you'll also need Automatic Train Operation – while having platform screen doors together with manual driving isn't impossible (compare the Jubilee Line in London between 1999 and 2011), it's not ideal and likely costs some capacity due to the more careful driving required for stopping accurately enough.
The other side of the same coin is also not good, to take too much risk. But all in all, current American culture looks insane from a distance. Especially concerning how kids are reared. Recipe for drug addiction and depressions.
No country’s media takes “if it bleeds it leads” quite as seriously as muang Thai, which features gore as front page news very regularly, and if they censored a particularly gory one, you can be sure your neighbour will post the uncensored version on FB.
Literally the only thing more compelling to a Thai newspaper reader is a photo of a staged crime re-enactment with the suspect surrounded by policemen and various people pointing at important things.
Nobody is going to court for triggering in Thailand.
The insane culture of litigation in USA is very much a USA thing.