An belief based on anecdotal evidence:
Ray Bradbury and
Oriana Fallaci (both writers) have
attempted to
just go for a walk in
Los Angeles.
Each were stopped by the police, who were quite suspicious
of this activity and asked questions like:
In the end, the police compelled them to get in the
police car so that they could take them
somewhere.
Bradbury wrote a short fictional story based on his
experience. He confessed to Fallaci that it had
actually happened to him.