Dealer actually showed me the trunk and door features when I picked up my car saying that, "There's no way you can lock your keys in this car!".....
Not sure about other years or models, but for my 2012 SRT it's not 100% and can be defeated as I found out the first time I took my car in for an oil change. Had parked the car in the express lane for the oil change and went in and left the key fob with the service guy. I had just come back from the parts counter like two minutes later and I see the service guy and one of the techs looking through my drivers side window. Hmm, this can't be good. As I walk up, he turns and says, "You're not going to be happy about this..." My heart sank thinking - What the hell did they do to my baby?
He says to me, "We locked your keyfob in the car". My response was, "That's impossible, the door won't lock if the fobs in the car". He replies, "No, not with the button on the handle, but it will if you push down the door's inside lock knob and then shut the door....." He had done this without thinking as he said it's his habit when locking his car... He then says to me, "You didn't by chance remove the actual key from the fob before giving it to us, did you?" Why would I have?
Anyway, long story short, the wrote down my VIN, went to parts and got a spare key cut. After unlocking the door and retrieving my fob, they were going to snap the key in two to destroy it. Instead, I took it, cut off the black plastic end to make it uniformly thin and now carry it in my wallet along with my spare truck's door key - just in case!
No matter how foolproof they try to make things, there will be someone that figures out a way around it.....