I generally defend Yelp against a lot of mis-informed opinions but this is pretty bad. It's clear Yelp is hiding a lot of legit reviews. There's a decent case Yelp should be erroring on the side of showing not hiding. At a minimum, Yelp clearly needs to improve its algorithms. As the OP describes, a bad experience with a service provider could easily lead to a 1 star review from a first time reviewer. And these are very helpful reviews.