Rights

Why is it that the United States Government says we, as Americans citizens have certain Rights, but when we practice these rights we are harassed by law enforcement.
Take for example, there is no law stating that we must produce identification when stopped by the police without them suspecting that you committed a crime.
They can't force you to identify yourself if they don't suspect you of any crime, yet they will try to intimated you in to showing some I. D.
I Believe most cops don't even know this because most law abiding people will just show them their I. D.
It's when people who know their rights won't submit their identification, it becomes a problem.
If it is your Right, then what's the problem! Why are the police harassing law abiding citizens!?