It is the public themselves who establish what constitutes what “legitimate business” is on public property. Any “random passersby” are presumably the public also. It functions as a way to improve oversight in representative government, where public give some token “input” which is then acted upon in more or less arbitrary ways behind closed doors. It also serves to democratize the ever-spreading surveillance technologies, where public areas are surveiled with access hidden from the public. The hierarchical nature of representative bureaucracies means that there is more risk and greater damage done by decisions in the local town hall or police station than on the street corner, or home of the average citizen. So government officials need to be acclimatized to doing the jobs we elect and pay them for in full public view. It reduces the absurdities of us paying them to to tell us what they say we are having them do. (I know, that IS convoluted!)
What I am gradually working out the details of (among other things) is basically an automatic municipal key-card system. Instead of there being locked doors on town buildings, there are logged card slots. People who live in town are issued cards for access to town buildings, so that there is complete transparency as to what is done there.
