My impression of the SOP of those organisations, which I stress is based entirely on online hearsay so may be wildly inaccurate, is that they write to someone who they suspect has probably ripped something illegally, make a song and dance about the huge statutory damages that can potentially be awarded (under US law), and then rely on the fact that defending a suit will also (under US law) probably cost them thousands even if they win, so settling may work out cheaper even if they really have done nothing wrong?
The analogous organisations don't tend to try that kind of stunt here in the UK. Unless the copyright infringement is criminal, in a civil action our legal system currently only provides for actual damages to be awarded, and it's usual for the winning party to be awarded their legal fees at the loser's expense.
So unless there are some kind of statutory/punitive damages available for each lost photo in a case like this, it doesn't seem to be a comparable situation.
The analogous organisations don't tend to try that kind of stunt here in the UK. Unless the copyright infringement is criminal, in a civil action our legal system currently only provides for actual damages to be awarded, and it's usual for the winning party to be awarded their legal fees at the loser's expense.
So unless there are some kind of statutory/punitive damages available for each lost photo in a case like this, it doesn't seem to be a comparable situation.