Were kids always like this?

On my daily walk through my neighborhood, I pass kids waiting for school buses and adults walking dogs. The adults always smile, reply to “good morning,” and often swap pleasantries, while the kids stare without expression and say nothing, or more often, never look up from their tiny screens. Is this because of parental warnings not talk to strangers, has technology totally taken over, have kids been like this since they lived in caves, or is it a combination of all these? Other reasons?