Where are all the ex-employees and leakers exposing the shenanigans? I do believe they have salespeople that suggest paying to fix things, but I don't believe they can actually do that.

It seems like it would be an easy experiment for somebody to do. Find a local restaurant with some poor ratings. If they want to cooperate, pay a Yelp salesperson to "fix" the problem and see if it goes away. If they deliver, then you have a bombshell article that could go viral.