
It can be proven, very easily. All it takes is a little bit of IT skills and a basic understanding of networking. There are also immense amounts of incentive to prove it. Your information would be spread across every news network, and you’d be able to use it to sue any business that does it.
So, the only reason it can’t be proven is because it’s not happening.
Data breaches are already commonplace, though. People don’t really care about that, so news outlets don’t care to cover it.
This is vastly different and would be a new thing that everyone would be interested in hearing about. So many people think that this is happening, but have no proof. They would love to be able to say “See! There’s finally proof! I told everyone!”