It appears you have a lot of assumptions on how things should work. I would suggest you maybe sign yourself up for a ride along with one of your local law enforcement. Maybe instead of laughing at your kids remark you can use it as a teaching moment that officers are walking into an unknown situation all the time and they have no idea how the interaction with someone is going to occur, so they use the light to see better. It is also used as a protection, you ever look at that light and try and see where the officer is at? They can assess the situation with some concealment and determine any safety risks.
I’ll apologize for the officer that his ESP was turned off and didn’t pick up you transmitting that your a law abiding citizen with no intent to cause him harm or intentionally break the law. I’m sure he is sorry for scaring your kid while doing what he can to maintain a safety for everyone.