In theory a review hoster is supposed to evaluate claims and act on reasonable ones. In practice review hosters are terrified of getting sued and will take down reviews easily.
I suspect most local businesses hire "reputation fixing" firms to actually do this dirty work for them.
Aside: somehow businesses get moved - even major ones like a local McDo got moved to the wrong location. Takes weeks for corrections from when I report them. I really can't understand that one. This too could be a killer for a small business, getting shifted to the wrong location.
In a similar vein, I'm forever having to report our opening hours and things to Facebook as we don't have any (small craft shop, open by arrangement) and people insist on adding some.
It's all really weirdly handled. I suppose it's the presence of untrustworthy parties in such disclosures though Google should have enough trust signals to weight users input.
In any case, the scenario you're describing is decidedly not pay-for-play on Google's part, and thus doesn't really impinge on my response to OP.
I'll assume Google's reviews are at least somewhat likely to be biased (either way!) until reason to believe otherwise. The "you don't know the review wasn't posted by a dog" position.
Reviews can be removed if they are shown to violate Google policies. Also, legal action can be taken to remove a review. Google does not write law about what reviews are permanent.
I wish Google would be terrified of getting sued, but we both know this is not gonna happen.
My friend is a business owner.
She received couple one-star reviews on google maps from customers she never had (she’s a real estate developer, real estate is expensive, she doesn’t have many customers).
Wasn’t able to do anything about them.