There are sneakier ways to crack down on this that you’ll almost never notice.
I know of one instance where Foxtel managed to figure out which iQ box was being used to stream a Mainevent boxing match. Apparently the boxes have the ability to subtly watermark a feed with a unique code somewhere that Foxtel can look for and then trace. (EDIT Factcheck: I can’t find any evidence of this online, but definitely recall it being a thing. Would’ve been maybe 5-10 years ago).
I also swear a couple of times I’ve seen the middy glass in differing levels of full. What purpose that serves I’m not sure.
This is so that you can’t just work out what it looks like and stick a sticker on the TV. They change the level of the glass, the opacity and the exact location in order to catch this.
There’s certainly the non-subtle version of it where they just flash a very obvious code up on screen, with more control over the boxes I think Foxtel could probably do even better than those - but even if you just flashed it up for a split second and were recording the stream you’d be able to pluck it out.