> We did, and yet people did still often just come over unannounced, to the point that it that the unannounced visit - which was common enough to be believable, but not always welcome

The question is, what exactly is the relevance of mobile vs. non-mobile phones?

I think it really depends on the walking distance. If someone is your neighbor, there's not a lot of effort saved from calling or texting first.

Going back to the OP, these are two very different things: "you can just text them… or not even bother and check their socials to see what impression of a life they’re presenting today."

As far as one-to-one communication is concerned, a landland call is just as good as a mobile call or a text. But social media addiction is an entirely different matter. That's not even about announced vs. unannounced visits but rather about living in the real world vs. living in a virtual world.

> was a frequent plot point in various media.

I'm not sure that citing fiction is useful.