I know that old people tend to overestimate the cluelessness of young people about the specifics of old-timey stuff, but one thing I genuinely haven't seen a lot of people talk about with regard to how photography has changed it that in addition to the parts you all know -- that photos had to be "developed" and that cost both money and time and had to be done by a third party in most cases -- film for shooting photos came in discrete rolls of a certain number of photos.
I think that the biggest impact of that was what it implied for casual or utility photography.
If you wanted to photograph something just to remember how that screw went in, or remember the serial number, or get a better view of the pins on a thing, or whatever, not only did you have to bring it to a place to get developed (and enlarged if you wanted to 'zoom in') and pay for that, but you couldn't just take one photo and bring it in by itself. (Well, you could, but it was a massive waste.) You had to finish the roll before sending the roll in for developing.
So if you took three photos of your cat and then one of the serial number on the back of your television set, and you had a roll of 24 of film (a common number), you wouldn't be able to get that serial number photo off the camera and developed until you took another 20 photos to "finish off" the roll. And since they all cost money, you wouldn't want to just waste it on random photos of garbage to use out the film.
So sometimes it would be another year or longer before you'd get your photo because you didn't finish the roll of film until then, especially if you weren't really a big shutterbug.
And then you'd get a roll back and have no idea what that one photo was for or about, whatsoever.