The format, presentation, positioning, and theme of public service announcements. The universal (or not?) cultural message of the handshake as a sign of friendship (or perhaps just the simplest to depict graphically). Is this in reaction to something, or is it preemptive? I have not seen this in any other neighborhoods (or cities).
“Let us from this moment make friends
Flowers rely upon [their] scent and beauty
People rely upon [their] civility and charisma”
Consider the set of behaviors your local government most fervently wishes to inspire in you, and how they choose to convey those desires to the populace. Is it through physical, or digital means?
Also: A very interesting review of different contexts’ approaches to “handshake execution” – complete with relative strength, gender norms, handshake initiators, and more.