Oh yeah, one time I forgot to remove wine from my luggage (you are allowed to bring 2 bottles but it has to be removed and checked at boarding). They took the wine and left us a note in our state room that it would be available at the restaurant if we wanted to drink it for a corkage fee.
Yes and no. Kind of the same deal as the what the TSA does. Your luggage will get scanned via X-ray or whatever, then it's up to the person looking at the monitor to determine if it needs to be opened or not.
The reason things like this are made is to sneak alcohol past security. I use them at concerts. Seriously I can buy a half gallon of Jager for what 2 mixed drinks cost at a show. I don't even want to get hammered, I just want to watch some bands I like and have a good time without it costing me a small fortune.