Here in Ireland, much is made of ‘signing’ to oncoming drivers while driving. There is a vast, mystical significance to the finger(s) you hold up, the hand you use, whether you raise your hand from the steering wheel and/or nod (and how deeply/long/to which side), how long you hold up the finger/hand, etc. It is a language of its own which I’ve never quite fathomed, and can sometimes be your only interaction with another human for days at a time. And the whole ritual is determined by what that driver’s great-great-great-uncle said to your great-great-great-great-grandmother at the county fair the year the new queen was crowned (Anne, or possibly Mary).
Interactions do take place regularly, either in social circumstances (in local pubs, or after Mass), or in people’s homes (sometimes called ‘rambling’). They can be very short and intense with fast-paced speech from several people at once, or they could go on through the night and may include music, poetry recitations, and re-tellings of tales of local interest (like what their GGGU really said to your GGGGGM at the county fair).
However, all of these interactions are informed by generations of communication and knowledge. There’s a huge subtext that outside observers don’t see, and can’t appreciate. You don’t just know your neighbours well, you know their ancestors too.