it's all kind of wild to me. so different to what i grew up with....
though this term ('safe space') was not in use during my uni years (that i can remember), we did have minority student lounges in residence halls. they weren't to block anyone's speech. just to give minority students a space in which to speak freely amongst themselves, and a brief break from dealing with constant minority status everywhere else. (i suppose, at home, you'd at least have moments or hours like that in your own home, if not your larger community. living away, it was an attempt to fill a need/loss and ease a transition.) it was a positive thing.
people occasionally protested speakers on campus - and off - but i don't recall it ever preventing anyone from speaking or having their own rally or whatever. demonstration, counter-demonstration is the way i recall it. and it was all non-violent. suppose i lucked out on that aspect.
i do remember when 'trigger warning' was a new thing (to me, at least) on the internet. i thought it was so bizarre and unrealistic. lol i tried to do it once and i think i wrote something like 'bit triggery - but so is life' and then gave up on forming a new habit. however, you're right, that is something you do naturally for people you know and care about, without needing or wanting a shorthand phrase for it.
even though it's semi-easy to get used to the notion that people are decent enough to warn you if something is very graphic or disturbing (almost like a film or tv rating), it boggles my mind people get out of class over these things. hahaha! seems quite unfair.
also, potentially, the classes you take at uni level are to do with your career. how can you opt out of bits of the training?
i remember so clearly, to this day, a lecture in a seminar on the viet nam war when my favourite (many, many students' favourite) history professor showed us a film on my lai. he was a viet nam veteran himself. wonderful, brilliant, kind man. always honest with us. we were all sitting there, watching this film, horrified. then a vietnamese-american classmate ran out the back, obviously.... well, today i suppose some would say, 'triggered'. it was awful. he let her go. and within a minute or so, elbows and looks went around the hall. our professor was sat in the back, face in hand, quietly crying.
you need to have human moments, and witness others having human moments. it teaches you things mere reading doesn't. not just debate skills. things that can't even fully be put into words.
i'm sure most young people have that moment (or more than one) in school where whatever's going on (in class or outside it) hits too close to home, is too heartbreaking. you have more moments like that when you start working. but you get through it.
so, while it can be horrible, especially for very sensitive people who can carry mental images and memories for years - they're robbing these young people of the opportunity to learn about themselves, how strong and resilient they are; and (ironically) to grow their compassion. to feel the opposition to evil rise within themselves. getting the scope of injustices forms the type of person you become, and for some directly impacts their life and career choices. it also prepares you for facing evil in your own life.
which makes me realise, i disagree with the woman who was on your show recently, who commented about traumatizing kids by teaching them history. that it makes them psychopaths. bollocks. depends on how it is taught - and on the kid.
as, just recently, julian assange tweeted to someone: don't deny history. it doesn't go away.
lastly, sometimes i think the internet has been a huge influence this trend, as a separate factor from politics. in that we've all gotten used to the convenience of mute and block buttons, spam reporting, offensive breaking the tos reporting. even just the the freedom to click off the page or leave a site and never return. i think everyone has to admit to wanting these options in 'real life' sometimes. and traditionally, society hasn't been great at teaching about setting healthy boundaries (or many other tools for mental health). so, yeah, now people are trying to make offline life work similarly to online life somehow.
(ha. maybe the trolling, rudeness, and type-y agression online is contributing to these offline meltdowns, too.)