> Is it inevitable?

How would you change the incentives? The incentive for a restaurant to leave a fake review is much higher than the incentive for a customer to leave any review. For crowd sourced reviews, introducing a trust model opens the door to account selling/paid reviews. You can't really punish the bad actors or you open yourself to a different kind of abuse. You really need a PageRank equivalent for reviewers? Is there some feedback loop (like following clicks) to the things you recommended (and seeing engagement on that page from GA)?

I'm not affiliated with glassdoor, but I would hope that they already do some data analysis to weed out biased reviewers.

You're right that reviewers have less incentive to participate than the targets of the review, employers.

Is there a different business model where a site like Glassdoor could align their incentives with the free-user employees?