Does the message say “everyone in the world” or just “people nearby”? I think my parents would assume that “nearby” meant people physically in the vicinity!
Well, same pitfall: if someone is nearby is determined by the client and can be spoofed. Technically you could check a GeoIP database and also usecell phone + wifi information to make it harder. All of which can be chosen by the client (apart from the IP, but thats also not a big deterrent)
