I can't think of a way to weed out the false ones, though, other than to reveal their names and allow them to be sued.
Of course, that might risk revealing the existence of any positive non-customer reviews, and with a company of the sort this one seems to be, I'm not willing to bet that's the empty set.
EDIT: phrasing.
If the lawyers see that the reviewers were actually customers, and so a defamation suit against them is not justified on the available evidence, the lawyers would have an obligation under Rule 11(b) of the Federal Rules of Civil Procedure to not proceed.
Rule 11(b) says:
-------------
Representations to the Court. By presenting to the court a pleading, written motion, or other paper—whether by signing, filing, submitting, or later advocating it—an attorney or unrepresented party certifies that to the best of the person’s knowledge, information, and belief, formed after an inquiry reasonable under the circumstances:
(1) it is not being presented for any improper purpose, such as to harass, cause unnecessary delay, or needlessly increase the cost of litigation;
(2) the claims, defenses, and other legal contentions are warranted by existing law or by a nonfrivolous argument for extending, modifying, or reversing existing law or for establishing new law;
(3) the factual contentions have evidentiary support or, if specifically so identified, will likely have evidentiary support after a reasonable opportunity for further investigation or discovery; and
(4) the denials of factual contentions are warranted on the evidence or, if specifically so identified, are reasonably based on belief or a lack of information.
-------------
Lawyers take great care to follow 11(b).
A judge has been asked to prove that seven commentators are actually clients of the service — otherwise, said comments were slander. He or she can't ignore that; more importantly, that accusation is almost systematic from service providers who accuse Yelp of slandering them, presumably with non-existant users, and then racketing them to dismiss said comment (in actually, pay to chose which comment to put first). Having the receipt might help clear common issues: the user got the name of the restaurant wrong, the interaction happened before the owner changed, it happened ‘that night’, etc.
This is far from an isolated case: all services from the distributed economy (eBay, AirBnB, Blablacar, etc.) have to handle trust and find appropriate mechanism. There has been cases of good-grade racketing on eBay; AirBnB has proven fairly good so far; BlablaCar name itself is a great example of a non-binary rating. Hence the discussion.
If users of that service want to get their good back, a small claims court seems more appropriate than a Hacker News thread.
Of course, this requires so many additional layers of complexity (e.g. unique codes, local Yelp POS software, etc)that Yelp would never actually use it--it simply increases the barriers for writing a review. I guess the trick is in implementation. Maybe verifying purchases through transaction clearinghouses?
It sounds like you're not OK with anonymous reviews, even true ones, because you support stripping the reviewers anonymity even in the absence of any evidence that the claims are false. If all I need to get your identity is a bald and unsupported claim that you defamed me, then your review doesn't have a right to anonymity whether it's true or not.
The reverse of this is that by being anonymous, I can make any claim I want in an online review (he touched me in inappropriate ways!) and there are no consequences. Are there?
This article specifically talks about the fact that in most states it would be required for them to demonstrate falsity or damages, which they didn't have to do under Virginia law. Without this check such practice can be used to suppress negative reviews since most people wouldn't risk legislation.
And then article says that it's most likely unconstitutional and this is why this case is appealed in Virginia Supreme Court.