The OP acknowledges that, and in fact gives faxes as an example, because while some industries continue to use them, most people never use them anymore.
what became common in 60-70’s were Hari Krishnas soliciting at airports, outdoor concerts, but now almost never; in fact, I don’t see them anywhere in a long time
I didn’t see this upthread, but aftermarket car stereos. Between the advent of the 8 track, cassette tape, CD players, and MP3 players, there was a stretch from the early 1970s through the last 5-10 years when you could easily get the factory stereo replaced with an aftermarket ones of the specs you chose.
Now the sound system is integrated with the touchscreens in newer cars, and you can’t just yank the old one out and plug in a new one like you used to be able to. I just checked on Crutchfield (the mail-order go-to back in the day), and neither my pickup (2024 Honda Ridgeline), nor any of the others I was considering have any stereo units available aftermarket. Nor does my wife’s SUV have any.
Largely my truck just has a radio receiver and Android Auto/Apple Car Play interfaces; if I want to do anything other than listen to AM or FM, I have to hook my phone up and do it that way through Spotify, Audible, or whatever.
That’s a good one. That market must be as dead as the dodo.
ETA: and car stereo equipment was a HUGE market in the 80s when I began to drive.
It’s a potential future annoyance for me because while I do use a USB stick for downloaded live music, I still like physical CDs. My current car is a 2016 and has one, but I’m likely to buy at least one more car in my lifetime and I’ll probably have to settle for an external CD unit or forgo them completely. Which will suck in a very minor way. I don’t want to rip everything to a lossless format 
.
Probably getting there.
I actually did buy an aftermarket car sound/entertainment system two years ago, but that was for my 2012 Mustang, on which the factory-installed stereo had died. I was able to get a touchscreen system installed, including Apple Carplay, and it’s been a really nice upgrade, but I expect that that market (upgrading cars with older non-integrated sound systems) is probably pretty limited.
Upon closer inspection, it seems all the wannabe-pseudo-hipsters (though fixed-gear bicycles were actually hip perhaps 30 years ago?) have their flip-flop hub on the freewheel side.
Not sure if these have competely gone away - but car alarms.
In the 70s and 80s they were so prevalent that every single comedian had a routine about car alarms going off at 2am. It was a standard joke topic of conversation. There were stories of thieves who would ‘rock the car a few times until the owner got fed up, and would turn the alarm off, so they could steal it’. Anyone who left their cat out at night would get blamed for alarms going off.
Have car alarms nearly disappeared, or are they just better at not going off at inopportune moments?
I think they’re better now. Many (most?) new cars have built in alarms. Mine does, but I’ve never heard it go off. If you ride the Washington State Ferries, you’ll hear two or three go off due to the motion of the boat. Every sailing contains at least one announcement to “return to your car and silence your alarm.”
Also pretty useless in most cases, IMHO. Most car alarms in public places are so annoying that I wish the car thief would go ahead steal the vehicle so I don’t have to listen to the alarm anymore.
An alarm for your own vehicle in your own driveway where you can hear it and respond to it is about the only useful use case.
That’s the big difference. The car alarms in the '80s and '90s, which were the butt of jokes, and obnoxiously went off in the middle of the night, were nearly all aftermarket systems, in an era in which most cars still had physical keys for unlocking the doors and starting the ignition.
(I remember one particular alarm model, which was popular in this area in the early 1990s, which, when it was triggered, would repeatedly announce, in a loud, Robocop-style voice, “HELP! I AM BEING TAMPERED WITH!”)
Most modern cars now use electronic fobs for entry and ignition, and as you note, some manner of integrated, factory-installed security system. About the only time it seems like I hear a car’s alarm going off now is when the owner accidentally hits the “alarm” button on their key fob.
Our neighbors had a house alarm that announced “BURGLARY! BURGLARY! BURGLARY! YOU HAVE VIOLATED AN AREA PROTECTED BY…A SECURITY SYSTEM!” I always assumed the pause was to give an intruder just enough time to think “A guard dog? A Home Alone-style array of homemade booby traps? What, for God’s sake?!”
There’s a AAA repair center across the street from me and I hear at least one a day. Often in the wee hours. But usually only for a minute or two.
Or when the owner can’t find their car in a parking lot/garage.
(Not that I have ever been guilty of this practice.)
The useful part of the car security system is the immobilizer that prevents the car from starting when the key is absent. Sure, break into a car, setting off the alarm, to steal things inside the car, but the car is left behind. The counter example are recent models from Hyundai and Kia that did not have an immobilizer and became frequent target of theft.
I don’t know about ubiquitous and then going away, but car theft itself is something that for the people here born prior to 1960 did become very common, but has since decreased greatly during their lifetime. As the article below discusses, much of this is due to the introduction of factory installed immobilizers. The article additionally claims that much of the reduction in all crime during that time is due to the decrease in car theft.
Uniform Crime Reports (UCR) trends from 1960, and National Crime Victimization Survey (NCVS) are the source of the car theft data.
Don’t forget the once ubiquitous, “PROTECTED BY VIPER! STAND BACK!”
That certainly counts.
That period pretty much coincided with the rise and fall of electric typewriters. I bet it made the news when the first novel written on a computer was published, presaging the obsolescence of typewriters. My guess would put it in the late 1970s or early '80s.
ETA: I looked it up. My hunch was accurate. It was Spirals by Jerry Pournelle, published in 1979.
This reminded me of The Club, that vehicle anti-theft device. You can in fact still buy them, but it seems like nowadays I only ever see them on older cars, particularly classic 1950s / 60s / 70s era cars. In other words, cars that lack electronic immobilizers.
So I nominate The Club as something that, while it still exists, isn’t as ubiquitous as it once was.
Can you still get a Trunk Monkey?
My favorite was when there would be a particularly loud and intense thunderclap during a storm, and you’d hear the chorus of car alarms going off afterward.
Last Hare Krishna I ever saw was a guy in the full get-up standing on a streetcorner in Houston (Bissonnet @ 59 if you’re interested) trying to give me a “Karma Free Cookbook”