Some states you only have to verbally identify yourself to police. Some states you're required to show I.d. if requested. Some states you can decline a breathalyzer and other states you cannot.
And if you know the law then you should exercise your rights to the limit of the law. Of course they keep passing new laws to push the limits in the other direction. And I don't think anyone wants to be a test case for throwing out a bad law in the courts.
The problem is similar here in Switzerland with the exception that there are fewer laws and that the federal government has very little power (unlike the u.s. With its strong federal laws). For example, here in one canton you can grow 2 marijuana plants for your own use while in another canton you will go to jail for even a small amount of marijuana.