What did the cops say?

They followed them to school and told the teachers that someone called the police for escort.

There's nothing illegal about this and nobody got in trouble but it still sucks.

You are lucky they called the police and not CPS.

CPS have nearly unlimited ability to fuck with your family, whereas police generally can't fuck with you without probable cause a crime has occurred. There is no such process or due process with child protection services as breaking apart families and tossing kids into the abusive foster system is considered 'civil.' CPS doesn't require a criminal law be broken to take action and can declare weaknesses in your parenting for things as simple as dirty dishes in the sink or your refrigerator empty because you're at the end of your grocery cycle.

My kid was interrogated for walking about 50 ft 'alone' ( I was actually watching further away and intervened before the Karen got to the point of calling it in) on our own property.

In the middle of nowhere, rural desert. Random Karen drove by at the wrong place and time, saw my kid, stops and questioned. Unbelievable. Literally the second you give a child independence a Karen will appear like clockwork, it's insane.