I encourage everyone saying things like "I can't see them doing it," "it doesn't seem likely," "I wouldn't report you," etc to read this:
5. PROHIBITION AGAINST THE USE OF REPORTS FOR ENFORCEMENT PURPOSES
Section 91.25 of the Federal Aviation Regulations (FAR) (14 CFR 91.25) prohibits the use of any reports submitted to NASA under the ASRS (or information derived therefrom) in any disciplinary action, except information concerning criminal offenses or accidents which are covered under paragraphs 7a(1) and 7a(2).
When violation of the FAR comes to the attention of the FAA from a source other than a report filed with NASA under the ASRS, appropriate action will be taken. See paragraph 9.
The NASA ASRS security system is designed and operated by NASA to ensure confidentiality and anonymity of the reporter and all other parties involved in a reported occurrence or incident. The FAA will not seek, and NASA will not release or make available to the FAA, any report filed with NASA under the ASRS or any other information that might reveal the identity of any party involved in an occurrence or incident reported under the ASRS. There has been no breach of confidentiality in more than 30 years of the ASRS under NASA management.
Let me ask you this. Imagine you were doing 75 in a 65 and drove by something you thought was a speed trap camera on the highway. Now imagine there is a NASA reporting system for cars, where if you report your speeding in this zone you won't have legal action taken. A buddy of yours, a cop says, "don't worry the cameras only send tickets for people going over 15 mph over the speed limit."
Now you have two options, listen to your buddy who didn't program the particular camera and has no material assets (including dollars/jail time) to lose by giving you faulty advice. Option two is take 5 minutes to fill out a form so if they give you a ticket you don't get in trouble.
Is 5 minutes of time really worth a possible violation? You have absolutely nothing to lose by filling out the report, all you do is gain a big safety net should things go south.
I personally tell my students to print some out and carry them in your flight bag in letters that are pre filled out. If you feel you might be at risk of a violation, sit down and fill it out to mail it that day. I have 3 in my flight bag ready to go at all times. Better safe than stupid.