For last couple of centuries or so, each generation grows
up with unprecedented change in their lifetime.
And you think the cell phone is more fundamental than, say, the widespread deployment of telephones in the first place? Before then, there was no way to have a voice conversation with someone more than a 100 meters away.
When the polio vaccine was invented "church bells were ringing across the country, factories were observing moments of silence, synagogues and churches were holding prayer meetings, and parents and teachers were weeping. One shopkeeper painted a sign on his window: Thank you, Dr. Salk. 'It was as if a war had ended', one observer recalled." (Wikipedia for Jonas Salk.) That vaccine still saves the lives of 100,000s of children every year even when compared to the 1800s. For that matter, before penicillin you could die because of a rose thorn accidentally scratching your mouth, as the sad story of Albert Alexander shows.
Tell me, how is the cell phone a more fundamental change than these?
And then, every once in a while, a polio vaccine is created, and the world is different for everybody. I certainly think the WWW is one of those. Facebook might be (800 million people under one roof is something, but I'm not convicted it is really changing the world).
But, yes, overall, I think people tend to underestimate the radical changes that happened during the first half of the 20th century. By 1950, the "structure" of daily life was much closer to it was in 2000 than it was in 1900.
But then again, I think that the main difference now is the current rate of adoption of the new technologies. How many years took to build the electric system? How many years took the use of the mobile phone to become widespread? Everything moves faster and faster, and that's what is letting lots of people behind. They just can't adapt fast enough.
For example, my mother. Every time she has a new mobile phone, she asks me to teach her how to use it. I start saying, "Read the screen, think, decide and then press the buttons." Because, i tell her "if not, what will you do when even your TV has more and more menus?" Of course, she grumbles, but at least tries. And when she REALLY needs help to learn something, i help her.
And I see this pattern everywhere. Tech changes so fast now, that while a few people adapt extremely fast, and to some it takes it a little longer, to the rest, they're just tired of learning how to use new stuff, every now and then.
Let's take some examples. Your baseline is the cell phone. The first commercial mobile phone was in 1983, so you're suggesting a time span of about 25 years. (Before 1983 it was possible to connect a two-way radio through to the phone system, but that's not the point you're trying to make.) By 1988, friends of mine had car phones. The StarTac phone came out in 1996 and marks the start of "widespread consumer adoption." But I would say that it took until 2005 where it started to supplant having a land line.
The first commercial (pre-built and for consumer use) radio receiver was in 1920. That marks the start of the "golden age of radio", which ended when TVs became more popular in the late 1950s. Surely that was as fast as the uptake of cell phones.
Semiconductor transistors were invented in 1947. "Transisterization" was so fast that crew of the Minnow had a transistor radio (in 1964) and no one was surprised by it. Transitors made entirely new categories of technology possible, so that we had a transistor-based game console (Pong-style "tennis" and "racquet-ball") in ~1975.
The first commercial (synthetic) detergents were introduced in 1933 (that's when Dreft was introduced) and "by the 1950s, soap had almost been completely replaced by branched alkylbenzenesulfonates." Not bad for 20 years! Actually it was bad, because we then found out it wasn't that biodegradable and had to find a replacement.
The neon light was first presented in 1910 and "became very popular for signage and displays in the period 1920-1940."
Prohibition lasted for 13 years in the US, and had a huge impact on daily life. That surely counts as an enormous change.
Cosmetics didn't become popular in the US until the 1910s, and the flappers of the 1920 used it with a vengeance. (WP says that previously it was too closely associated with prostitution, but the post-war trend was a reaction to the previously popular demure look, and that "[a] skewed postwar sex ratio created a new emphasis on sexual beauty, and because of the influence of Hollywood.)
All these big changes took place on the same time scale as the cell phone. How then do you measure the amount of change now, and compare it to (say) the amount of change in the 1920s? When was the last time that most people were not "tired of learning how to use new stuff"?
What about the railways?
I mean, I love railways, I really do, but compared to a thing like our cell phones? It would even be possible (altough quite cumbersome), to entirely live just from this thing! (Do some programming/webdesign/consulting/whatever to make money, order food and everything else online and you don't have to do anything else.)
So long as we continue on our trend of exponential technological growth, this will be tautologically true.
That's presuming strong AI is possible, of course, which I think it is.
I don't think the cell phone is that significant on its own, though it is up there with the changes others have mentioned.
What this generation is seeing isn't one massive change: it is seeing a greater concentration of significant changes than previous generations, and some of those changes when grouped together have greater impact than they would individually.
edt: i meant this to appear underneath the comments with other pretty meaningful inventions that caused huge social change
Or the transistor?