2. They're illegal because speeding is illegal. I don't know what the fines for them in QLD are.
Well as it always goes, just because I have a radar detector doesn't mean I will speed, at the same time just because someone who doesn't have a radar detector does not mean they won't speed. And it's not like people who drive wrecklessly won't be caught anyway, whether they have one or not. I've had one for the last 2 years or so, and I know many people who have one, and none of us drives like an idiot. It just helps you become more aware of your situation and speed limits, which, in my opinion, improves safety
I've never had a ticket before I got a radar detector and I've never had a ticket after I got one.