Proximity marketing targets people by where they are rather than who they are: near the store, in the aisle, standing at the screen. The mechanism might be a geofence, a beacon, a scanned code or simply a screen in the right place.
The appeal is intent. Someone thirty metres from your door is a materially different prospect from someone browsing at home, and the message can assume context: stock in this store, a table free now, the aisle they are standing in.
The caveat is that the phone-based versions all depend on permissions the visitor has to have already granted, which in practice means an app they installed and left running with location enabled. That is a small fraction of any venue's traffic, and it is the assumption most proximity proposals quietly rest on.
Screen-based proximity needs none of it. A display in the aisle reaches everyone who walks past, with no app, no consent flow and no personal data, which makes it both the cheapest form of proximity marketing and the only one whose reach is not shrinking as platforms tighten location access.