Okay, but trains are legitimate ground, because the TSA has previously set up in the New York subway (http://www.cnn.com/2012/01/28/travel/tsa-vipr-passenger-tr

Okay, but trains are legitimate ground, because the TSA has previously set up in the New York subway (http://www.cnn.com/2012/01/28/travel/tsa-vipr-passenger-train-searches http://www.cnn.com/2012/01/28/travel/tsa-vipr-passenger-trai...). To some extent, stop-and-frisk (as I linked to above) means that there are governments in the country who feel that they can search you while you're walking around, so my bringing them up isn't that silly. Again I ask, what modes of transport are privileges and how many of them can we take away (not because you are incompetent at controlling them, but because you refused to subject yourself to a search) without completely destroying freedom of movement?