I think a lot of people are getting caught up in their own self-importance here.
Policing a society doesn't mean policing everyone apart from you. You know what you are doing, but I don't expect many police officers carry crystal balls around with them. Consequently, it is reasonable for anyone, in a well-policed society, to be stopped and questioned by a police officer, particularly if they're doing something odd. If you're doing nothing wrong, they'll move on. It's a sad fact of life that particular demographic groups (young men, for example) are more likely to be involved in criminal activity, so naturally these groups will attract a disproportionate amount of attention if they're doing something which the police officer's experience suggests might be suspicious.
I can sympathise with the tiny minority of people who are genuinely mistreated by the police. But ill-socialised children who think they 'know their rights' and refuse to cooperate really aren't helping.