That's interesting about the students. Were they geeks? Also was it definitely a case of 'we don't want them' or was that just a cover for 'we can't afford them'?
(Of course you also see a lot of heads buried in phones as soon as you step anywhere near a university – or anywhere else.)
This also applies to graduates. People in the 25-35 age bracket around me have less smart phone usage than what I experienced in other countries. Among my friends almost anything is discussed face-to-face, via phone, or via email (in that order) and if I have to wait until the evening for an answer that's fine.
It reminds me of a cool classic sci-fi movie about consumerism. John Carpenter's "They Live". I watched it as a kid but it started to make sense later.
https://en.wikipedia.org/wiki/They_Live
"Nada quickly discovers the sunglasses have unique properties: they reduce the colors of the world around him to black and white and allow him to see that media and advertising hide omnipresent subliminal totalitarian commands to obey, consume, reproduce, and conform. They also make clear that many people in positions of wealth and power are actually humanoid aliens with skull-like faces."
Obviously it depends where you are in Europe. In the UK I'd say we're a lot more towards the American end of consumerism but they still take it much further. Food is the biggest jump for me. I still remember my first time in America and I was out for dinner. My friend suggested we split a meal as the portions were large. I still couldn't finish mine (and I eat quite a lot) and she brought home a doggie bag with enough food for two other people. And this was quite a nice restaurant too where I'd have expected smaller portions.
Owning a beaten-up low end smartphone for the utility (e.g. being able to check public transport times anywhere) is well within the "compromise" range for just about everybody, playing the "latest iPhone every fall" game would be clearly out of range for many.
The "going low-tech" crowd just happens to be very sensitive (and hostile) to signs of consumerism and this perception blinds out all traces of utility they might see otherwise. "I'm too smart to play a game i can't win" is a very desirable status message to send and it's best conveyed by an old Nokia. Being in Berlin and having a good time also makes them pretty immune to the nagging question of "am i missing out on something big by not having a smartphone?" that is driving smartphone adoption in other parts of society (e.g. the elderly).
PS: oh, and one argument in favor of "can't afford" crossed my mind nonetheless: some might actually think that they can't afford a smartphone. The really cheap options are not heavily advertised, so non-technical people in Germany often think that all smartphone ownership would be as expensive as the ridiculous "1€ iPhone" contracts they see on the billboards. Avoiding smartphone ownership because you are scared of hidden costs would be a very, very "german" thing to do.