Paranoid suburbanites. In the US, happened to me twice as an 11/12 year old north of Chicago, just for walking down the street - and once in Charlottesville, in the burbs, aged 24 - again for walking down the street. Once in Germany, aged 10 in a suburb of Frankfurt - I was sitting in a park with a book. Oh, and once in the U.K., in Hatfield aged 22, waiting outside my girlfriend’s house having arrived a bit before her.

Only got put in a cop car in the US - in both Germany and the U.K. they realised I was just doing normal human stuff - both childhood occasions in the US they gave my parents a talking to, as an adult they were unreasonably suspicious as to why I would be walking rather than driving, but let me go with a warning to drive in future.

So - the problem is the police, and the justice system, as curtain-twitchers live the world over.