I have a shady question about VUDU's Disc to Digital program my friend mentioned.?

So my friends and I were kicking it at my place, surfing to something to watch from our phones to watch together on the big screen.

I saw a thing on VUDU that said Disc to Digital, clicked on it and it said I can convert my DVD/Blu Ray to Digital by scanning the bar code and my first one is free. After that, it's $2 for Blu Ray or $2/$5 for DVDs depending on what resolution I pick.

I told my friends about it, and I said out loud "which movie should I convert?" When one of my friends started to ask more detailed questions like, just the bar code and nothing else.

Which I said, apparently yes that's all it said for me to do.

So she asked, what's to stop me from going to Target or Walmart and grabbing the newest movie and scanning the bar code from that?

Which I wondered myself, what is going to stop people from doing that? I mean, from what I can think of the bar codes on the box are going to be the same. So what's going to stop me from going to Target and scanning let's say the new Star Wars movie and getting a free Digital Copy?

It does say GPS location services has to be on, so I'm assuming it's just going to detect if you are in a retai store or not.