You fail to understand the nature of randomness. Sometimes randomness can produce a long string of similar responses. There could also be non-random factors, like where you have lived.
It seems to me that a few people on this sub share the same experience, and then some others don't.
It also for some reason is very different from the internet ratings of the services. To me, this implies that either this sub is biased, or the ratings are biased. I see maybe slight reason to believe the ratings over this sub, because:
They are tabulated.
Some of them require non-anonymous accounts.
There are more responses.
It's clear that the opinion toward Uber in this sub sways strongly in favor, but it's not clear whether that's because of personal experience in every case of an upvote.
There easily could be numerous accounts spoofing favorable opinions of Uber and upvoting favorable opinons, although there's no proof that that is the case. I think that it is more plausible that Uber would manipulate opinions or ratings online. Uber is more modern, more internet saavy as a company, and probably hires people who have computers/are more familiar with computers. I also know that there is some personal interest here, some Uber drivers on this subreddit.
Of course, with the ratings the major risk is that taxi drivers rate Uber down, which they can easily do as there is no direct proof that they are a taxi driver that is easy to obtain. However, if you look at the actual reviews, this seems implausible. There are people from out of town, people who don't fit the typical demographics of a taxi driver, etc. There also is central organization at Uber, whereas there are multiple taxi companies. Though, because they share the same goals in this way, they could have all come up with the same thing. Still, it seems unlikely, because most of them don't seem that corrupt, at least outside of Boston proper. Neither does Uber to be fair, though. It also seems less likely that cab companies would hire people to write good reviews for them.
Maybe the ones in Boston proper are really terrible. It seems that way from the ratings. I've always lived in Cambridge, Somerville, or Medford, so I probably have a different experience.