More and more people are using Google Maps to find businesses near them. My friend Lynn gets nearly all her business through Google Maps searches. This has nothing at all to do with a "normal" Google search. It is a completely separate system.
The critical first step is for a business owner to go to Google Maps, search for themselves within Google Maps, and "claim" the existing entry. Google should already know about every business in the Google Maps interface. They did that project quite a while ago. So right now the entity is sitting there unclaimed and without valid information. The owner needs to prove they own that spot so they can gain access.
Google already knows the address. So what they do, when they get a claim request, is send a physical letter TO that address. The person then receives it there and follows the instructions.
This prevents hackers from getting access to that account, unless of course the hacker physically breaks into the store's location
Let me know if this part is clear. It's about physical locations and physical mail being sent there.