I don't think those are very real concerns. If you have roaming gangs kidnapping car owners you have other problems to deal with. But either way, it seems like the naysayers here for some reason just don't want self-driving cars to happen, and are finding any and all excuses for why they will never work. I'm saying that if there's a will there's a way. We've made way larger sacrifices for other modes of transportation in the past. I'm guessing these are the same people that would have claimed that cars are impossible because nobody would want to build tens of thousands of gas stations to accommodate cars etc. Compared to the changes we've made for cars, even designing our entire cities around them, the changes needed for self driving are minuscule. The benefits are maybe not the same but it's certainly the biggest revolution in transport since the airplane.