Very interesting question, and already in my three and a half decades on this beautifully dysfunctional planet, technology has changed absolutely everything both subtly and profoundly. I like your example of leaving one's phone at home accidentally when going out, as I will often do that on some short walking errands, and even then I catch myself feeling anxious. Ridiculous, as I remember when I was a teenager my friends and I already recognized that the simple dumbphone (think Nokia 3310) was a "tether" where you were at someone else's beck and call. A curious time to reflect on the balance between the convenience of technology and the "culture" of personal freedom. Even when I started college in 2005, the idea of having to go through the rigmarole of interrogation via. personal device to display a QR code to merely gain entrance into a lecture hall/cafeteria would have been pure dystopian science fiction, but here we are.
I actually held onto my flip-phone until about 2011, but got my first iPod touch in 2008 and it seriously was the most slick piece of mobile technology I had ever used, bar none. Of course it didn't really do anything new, but the pure accessibility of it I knew would change the world. For me, something we all take for granted now, having GPS navigation with a live-map overlay in our pockets, changed my life completely. We had already been using computer-aided navigation even on my father's PC going back to like 1993, (I think called Microsoft AutoMap or something) but printing out directions, even though a huge leap forward from trying to use folding maps, was nothing compared to the cyborg-like convenience of being told exactly where to go, what bus/train to take and their schedule, what stop to get off, etc. Something as simple as going to a venue or street fair before smartphones involved some degree of independent exploration and guesswork. The art of asking neighborhood locals for directions and following their unique diatribes is a subtle thing barely anyone does anymore. It was often messy and inaccurate, but there was that mystery and wonder.
I'm really glad I came of age before these devices completely contaminated culture. The nascent smartphone era was a lot of fun, but I'd say by 2013 (when "selfie" was added to the Oxford dictionary) the die was cast and now many humans exist in a purely hyperreal, cyberdelic reality they call normal. I do too, in my own way, just fully aware of it and it's consequences. Also screw those QR code menus, heh.
