Do you think trigger warnings can be narrowed down enough? Because the lists of things that require trigger warnings that come out of the community that typically pushes for them are long and vaguely defined and derived often using capricious and frivolous interpretations. For example rape is rape, but a "trace of rape" can be lots of things to lots of people. And to comb through something for any traces that may trigger somebody doesn't sound like a realistic task. Can you really track all aspects that may remind someone out there of something they've experienced?
It seems like practically speaking you can only cover the big things that are already covered by most content warnings like violence, sexual violence, etc. And for the rest content has to be checked by someone for a specific individual and their specific case.