It certainly sounds like they would be sending it to the address provided by the scammer. The issue is their system assumes the first person to interact with it is trustworthy: gives a real phone number and address. If that first contact with Google was MITM'd, they seem to have no way to develop an un-compromised relationship with the real entity.

I don't think it does. The postcard should go to the place where the customers go, so for a restaurant its the place with the tables and the food and stuff.

If the address is different than the address of the shop-owner, then how would a user who uses google maps get to the shop? And why wouldn't the shop owner just create a new, correct listing?