Clearly you have not been running a small business.
Some reviews are posted from time to time by people that are not even customers or stopped by the business; for some dumb reason they post a 1 star review.. And that review usually stick and doesn't get filtered out...but other reviews from true customers posting 4 to 5 stars reviews disappear usually in less than 24 hours after they were posted.
Regarding your ad hominem statement, I've been running small businesses since my first in 1996.
I've not witnessed this scenario you present and I have no relationship to Yelp that might give me some greater insight than anyone else. I have no idea why this might happen; I'm limited to communicating based on my own observations.
Spam filtering is hard? You are a programmer, imagine trying to find a way to objectively and fairly filter reviews. Unlike with emails you don't know whose labels to trust. There are good business owners who will only report spam reviews as spam. Then there are bad business owners who will report negative ham as spam to try and boost their reviews. Finally, there are bad business owners who will use shell accounts to submit positive spam and then mark it as ham.
In general the labels from business owners are not trust worthy which gets them into these situations. Thus they try and create other ways of identifying spam: like user engagement on the site. However, engagement doesn't always work as a metric as spammers can cultivate spam accounts by posting lots of "legitimate" reviews on unrelated businesses and then sell reviews from the accounts to attack (boost) specific businesses. Finally, users who have a tremendous experience at a business and go on Yelp to give them 5 star reviews may have no history with yelp except as a passive browser. The engagement metric will weight poorly for their review.
So what is to be done? I don't have a good answer for that. This seems more like a human problem than a technical one. The best course seems to be: act ethically, serve your customers with compassion, write responses offering assistance to negative reviewers, and if you feel Yelp (and similar review system are a bad idea) put your advertising dollars elsewhere.
They are various ways to solve the problem but again it is not in Yelp's interest. Yelp's business is about selling Ad and they don't really care about the underlying issues.
One simple thing that could be added to their system was a way to verify that a reviewer did really have a business relation for posting a reviews. They are various ways for solving that.
Even a simpler approach: why hide those reviews. Keep them here and introduce a way for other viewer to rate the reviews aka 'X people found that review helpful'. That way all reviews are visible and the random person reading the Yelp page can decide for themselves.
Unfortunately Yelp and their filtering system have a different approach and instead usually end up filtering real customer reviews and leave the more 'spammy' visible. Then after a few weeks like that, you will receive a phone call from Yelp sales folks telling you that if you purchase 'ads' then your potential 5 stars review (if any are left visible) will be pushed to the top.
There is no relationship between the sales calls and the filtering algorithm. That is what the dismissed class action lawsuit was about. All "evidence" people have is purely anecdotal.
Verifying a "business" relationship may work but it still won't solve all of the problems. You can still pay people to show up at your restaurant, pay with their credit card and write a five star review. You can still pay people to show up at a competitors restaurant, pay with their credit card and write a one star review. It simply increases the cost of the spam (which is a good thing). They should probably create a way to do this but it won't solve the fundamental problem: the reviewer pool is an unreliable source of information.
"X people found that review helpful"
A helpful review is not the same as an accurate review based on experience. I would find a well written review helpful. However, the review could still be inaccurate or fake just well written. This is simply another data point for spam detection and one with many confounders at that. One has to simply google around about the state of Amazon reviews to see the flaws in this approach.
Once again. I stand by my assertion, detecting spam reviews is extremely difficult because it is a human problem.
I can vouch that this exact scenario has happened to one of my small businesses. Multiple reviews from actual customers are filtered out, but a negative review from someone who has never interacted with our organization is displayed normally.
Were your actual customers regular users of Yelp who have reviewed other businesses actively?
We can pick apart Yelp's model and likely should, but it does appear to discount "drive-by" Yelpers who only sign up to give a good review to a single business.
Yes, in my experience I have seen reviews from regular Yelp folks (aka posting maybe a review once or twice a month) see their 5 stars review vanish in less than 48 hours... While at the same time a person posting a 1 star review without any other review posted prior and even after stick forever.
This is a classic 'Yelp' business practice and many business owners you can talk to will have many of such reports.
No, I believe most of the reviews were from first (or second) time yelpers. I can understand where they're coming from on a macro scale, but at the individual business level, it can be irritating.
If their ranking algorithm is pushing reviews with high page-views to the top, then perhaps it's as simple as negative reviews getting more attention, either because negativity draws people in or because people are more interested in trying not to have an awful experience than in having a great one. On the other hand, if the algorithm is optimized around other values (credibility, for instance), then it wouldn't make sense for reviewers with no history to get their reviews pushed to the top. Hard to say, given that it's a trade secret.
What kind of explanation do you have?