A nice discussion here:
2. Trigger warnings are already common, and have been for a long time.
hbo violent content
Every time the news warns you before watching a piece of violent video footage, that’s essentially a trigger warning. When you watch HBO and there’s that pre-show list of all the violence, nudity, and sexual content you’re about to see, that’s a trigger warning. All we’re asking is that some of those trigger warnings list “rape” instead of lumping it under “sexual content,” or say “violent hate crimes” instead of “violence,” for example. It isn’t wrong to ask that they let us know which episode of American Horror Story will cheaply involve rape to move along a mediocre plot. Some people need to know that kind of stuff in advance.