If enough people answer with, "Show me yours and I'll show you mine!" when they're asked for their papers, then there will be far fewer unnecessary identity checks, because...
If an officer who has asked for your papers refuses to identify him- or herself, contact the local police as soon as possible. If the officer is in a car, take down the registration number. Ask for his or her rank and try to find out what the officer's name is. Then file a complaint against him or her. If you can't get a name, file a complaint about the entire incident to the police chief. And let us know about it: klachten@gelijkoversteken.org. We want to report abuses on this website.