I wonder the extent to which it's possible for such body shops to get accounts that are believed by Google to live in the U.S. (or fake-review destination country of choice). I see sites that purport to offer such accounts for 30-50 cents per account. So I guess it's not that expensive. I wonder how often these accounts get burned and how much revenue they generate with each account beforehand.

That’s exactly what services like luminati.io (holavpn) are used for. While accounts can be purchased, they then need to remain tied to a US IP address to avoid being restricted.

There are some legitimate uses to proxy through residential IPs, but I wonder what percentage of traffic through luminati is legitimate. Wouldn’t be surprised if it’s a single digit percentage.