You have to have a certain amount of trust to do what we do as self-pubs.
I sometimes wonder if that trust is misplaced. How hard would it be for Amazon to tell you you've sold 100 copies of your latest epic, but in reality you've sold 150? How would you ever know? How would you ever prove it? A lot of people (mostly on Youtube) like to scream that Amazon (and other big corps) are evil and steal from us all day long. There is always the hope that they are just screaming in the wind.
It isn't just sales either, as this thread is showing. How do I really know that my AMS ads drew 20,000 impressions yesterday? How do I know that it was really just 2,000, but AMS inflates it so I'll keep buying ads? FB makes its money from ads, so now we know that they will inflate the numbers so we'll buy more ads, putting more money in their pockets. How do we really know that all of our advertising avenues aren't doing it?
Like I said, we have to have a certain amount of trust. I just hope we're not pissing into the wind.