I hate the word 'loophole' used extensively by the media to describe this.
First of all, I hate the word 'loophole' used extensively by the media to describe this.
This was never a loophole, it was a perfectly legal means to watch 'catch-up' BBC iPlayer up until 1st Sept, within the defined rules. It was only that it became 'more mainstream' to watch just catch-up, (with licence fee revenue dropping) that the Government decided to stem the tide and make it illegal to watch BBC iPlayer catchup services after 1st Sept, without a TV licence.
Its easier to block bbc.co.uk/iplayer in your home router than worry about it, once its blocked thats it.
I needed to write to TV licencing because in the past I have told them that I watch catchup services occasionally, so I needed to show that I understand the new legislation changes, and that, watching iPlayer catch-up is no longer possible. I'm disappointed a paywall/username/password wasn't introduced.
Capita have a job to do, I accept that, most incriminations are by invaders themselves, I believe there is some 'detector technology' in the iPlayer iOS Apps /iPlayer Android Apps. This maybe in the form of a detectable high frequency pitch, certainly the Apps have access to a lot more device information, over web access.
Most incrimnations result because they do what you put forward as a solution, which is don't reply to Capita/TV licencing letters - and isn't.
Far better to be upfront, pro-active in writing/dealing with TV-licensing, you get nowhere just ignoring them. That's just my experience from having to deal with them every couple of years, just to confirm nothing has changed (or in this case where it has).