Perhaps more to do with Link's own social inexperience, than a lack of common cultural points. Though handshaking perhaps still wasn't the most common, back in Hyrule.

Deftly, Link taps at the Slate's screen, soon bringing up the map function. He might not be very familiar with digital communication tools but this, at least, he's well practiced at using.

When he has the map open, he holds it out so Layla can see. A tiny icon of a chest marks all of the locations of the Sylphid's depots and post offices.