I think the technical limitations make it too difficult to use Internet methods to catch people who haven't paid their license fee.
I was thinking of something along the lines of a subscriber service like Sky or whatever. As they used to say in the opening to the 6 Million Dollar Man, we have the technology.
As for knocks on the door, we had one 20 years 51 weeks ago. (We moved here 21 years ago). Didn't have a clue about the TV license then, especially as we were moving straight into a company flat (those were the days…) and all the details were supposed to have been taken care of. I happily let the guy with the clipboard in, and after looking at the television he more or less said "Papers please?" It was sorted amicably.
Fast forward years later and we decided we weren't watching enough to justify the fee, and disliked some of the aspects of the way the beeb were conducting themselves anyway, but as they say, that's another thread.
They're capable of awesome television in between lashings of less awesomeness, and I even love some of the advertisements for themselves they've done over the years, like Perfect Day, and Free Runner:
[youtube]https://www.youtube.com/watch?v=3xR0smB1V58[/youtube]
Alas.
Here's one that's still up, though it's plugging radio, which of course you don't need a license for:
[youtube]https://www.youtube.com/watch?v=zolqJkmia7Y[/youtube]