If it expands to China, India, and other similar places, they will probably pay $1. They'd be foolish to pay the same amount. As a shareholder, I'd be worried that Google is trying to do a bit too much.
Ahh damn, sorry. I didn't even see that post In regards to it being hard, I don't know. You're not going to convince everyone to send back a postcard, but you can also have them validate it online. Basically a week or two later, you could easily pop in with a laptop and wifi, show them the listing, and have them confirm it on the spot. I'd hope the online confirmation process isn't too annoyingly long. I also imagine it would work better in small shopping districts on a quiet monday morning, etc. Print off a faq sheet with all the details they need to know, and have some fields for them to write down what you need. Snap photos as you do it, and then pick up the sheets once you've done the whole street, etc. Rock up later and have them confirm it all while you're there. I wouldn't expect people with a lot of sites to manage to bother, but it would be perfect for university students and the like!
We are simply working for google now. $10 is cheap. Google can generate more $$ from these business owner, eventually.