Back before evil censoring leftists took control of college campuses and took away all of the free speech, it was common for my various faculty acquaintances and friends in the humanities to have to try to accommodate the various delicate sensibilities of conservative religious students who believed that their religion did not allow them to read certain books and (especially) see certain films. While the degree to which any particular accommodation is "reasonable" in these circumstances is debatable, they were a regular, if not extremely frequent, type of request that faculty members had to deal with. None of this ever made the news or inspired a billion frothing think pieces about how college students were censoring us all, or about how the delicate little flowers needed their safe spaces because the kids today are weaklings. But the substance of the requests was the same: warn me about the material, let me decide what I can and can't read/watch, and find alternative assignments for me if I ask for them.
Those who bleat loudest about trigger warnings (which, whatever their merits in any particular context, have not actually taken over college syllabi, though it's fun to pretend they have) would probably be leading the charge to demonize the faculty who were teaching their precious little darlings using some of the materials they are actually using. Faculty sometimes teach using violent and pornographic films and novels, including sexual violence. And gay stuff! Lots and lots of gays stuff. Some of this would horrify those horrified by trigger warnings which they imagine are regularly applied to The Great Novels they probably never read but know are truly great because white male canon. Those also include sex and violence, but the right kind.
Forcing faculty to stamp trigger warnings on everything would just lead to the equivalent of "Warning: this syllabus may contain nuts." That's neither smart nor helpful. But having a bit of awareness that this stuff might actually be a bit shocking and, yes, traumatic to 19-year-olds who haven't ever been exposed to it, and dealing with that accordingly, is perfectly appropriate. As I said, it's nothing new. Conservative religious students have been asking for it for years.