They have road blocks aka 'sobriety" check points now. Do you really think that if these devices are installed that the road blocks will go away? I think not.
OF COURSE NOT! Nobody has really mentioned ho the insurance companies profit mightily by these sort of things, to the point they can afford to buy just about every town a "DUI Enforcement Unit". Take a look at how many towns in your area were given one of these fine vehicles at no charge by an insurance industry gorup, or an insurance company directly. Allstate bought the one for my town. I'm sure they've been repaid 10 times over inthe 2 years it's been since they did so.