I'm not saying you're wrong, I know that I had to buy a TV license when I moved in with my SO, but I'm not sure if that's because we bought a TV (we never watch it) or if my SO just did the necessary paperwork out of habit.
For example a TV with built-in tuner and no other equipment (no DVD player, no console, etc etc) they would likely be able to argue that you do watch live TV even if you weren't witnessed doing it, whereas a TV that isn't connected to any aerial but is connected to an Xbox you could probably convince them otherwise without even leaving your own home.
I suspect that they would also lean towards giving the benefit of the doubt, because it's such a minor crime that if there's a chance you'd be found innocent in court, or that they'd have to spend time investigating further, it's a much better use of their time to move on to the next person.
But I could well be wrong.
Well that's probably why the law was updated (if indeed it was) - the same rules used to apply to PC TV-tuner cards too though, having a tuner card was considered "receiving means" and meant license was needed for any premises where that computer was plugged in.
We have a TV but haven't had broadcast TV for many years, since our aerial blew down and we had no money to get it fixed - we stopped paying the license then as we no longer had receiving means. Just watch DVDs, iPlayer and the like (and use it for Wii).
As an aside, you can use a laptop to watch live TV anywhere (in UK), as long as you have a license for your "home"; but if you plug it in (eg to charge) then the premises you're at need a license!