It's about the career ladder, stupid!

"They're not setting out to ruin peoples lives, its their job to investigate."

Yes, and it doesn't matter a whit to any one of the "investigators" if the people they are investigating are guilty or not. All they care about is getting another rung up on the career ladder. What could it possibly matter to them, that thousands of innocent people may have had their lives ruined, and that a few score are dead, as long as they get an extra 300 Pounds Sterling annually?

There are ways to determine guilt when you have the server records in hand that don't involve confronting the owner of the credit card - like for example, if the IP records indicate that the files were downloaded to a computer in Romania, but the credit card data points to a UK resident, it's a bit odd that he traveled halfway across Europe every few hours to get a few files, isn't it?

But never mind, The investigators will get their promotions, and that's all that matters.

And the real kiddie porn customers are probably laughing themselves silly as they watch their neighbors taking the fall for them, all unknowing.