An interesting thing about paid reviews - you can prove that the reviews are fake, but you usually can't prove that the business itself actually paid for those reviews. In a hypothetical world where companies with fake reviews are regularly discovered and lambasted in public, it's easy to imagine a sinister metagame where unscrupulous small businesses can buy bad good reviews (i.e. 5-star reviews that are obviously fake) for their competitors to make them seem sketchy. The folks selling the fake reviews certainly don't care who's paying. There's no obvious solution to me for that potential problem aside from stopping fake reviews before they're posted (which feels like the kind of thing that's much harder than it sounds); thankfully it doesn't appear to be a very common thing yet.