I was also disappointed when I first took a little time to look at what was going on inside the KVS black box. That was back in 2011, when I was still a subscriber.
KVS got sufficiently rattled by criticism/questions from people who'd understood what was going on for some time (some of whom have contributed to this thread) to make a rather unwise move (from his point of view): he started a discussion on milepoint. The key points were summarised in
this post.) The thread was quite enlightening until Randy Petersen stamped on it.
What I felt then still applies: If you buy an iPhone from a stranger in a bar, or DVDs at a street stall far from home, you shouldn't be too surprised to discover that what you've purchased isn't fully above board. Similarly, people who download 'warez' software or trade passwords are aware of what they're doing. KVS is different, in that most users don't have a clue what's going on.
I'm newly realizing this.
So is ExpertFlyer any better, data-source-wise?