Exactly, numbers stations were a big thing in the 70s-80s.
In those days carrying a SW receiver was pretty standard and almost every country had a world service radio station that people would actually listen to.
These days using the internet makes a lot more sense yes, both for tourists and spies. Because spies want to be where the mainstream is to avoid detection.
A what now? :) Are you sure that is a lot harder to explain away than literally any computer gizmo looking object? (Today, not in the 70ies)