basically, put it this way: if a cop stops you and asks you for your phone--what are you realistically going to do in that situation the moment they don't respect your "no" and begin to pressure you, threaten you, and decide to throw the legal book at you (however dubious) for saying no? for most people, the answer is going to be "just give up the phone and start complying with the cop" even though that is not something the cop should be able to do. because at the end of the day they have a gun, and can put you in jail (or at least make your day hellish) more-or-less unilaterally, with very little recourse for you unless you want to do expensive litigation.