First did the school complain? If the school did not complain, did the officer ask the school if there was an issue?
A public school doesn't need to complain. An officer caught the guy using electricity from an outlet on public property without permission (a.k.a. theft). A police officer acts on behalf of the public. The article stated the officer checked with the school system prior to making the arrest. The guy was picked up 11 days after the incident.
If there was an issue, I am sure the officer or the school could have approached the man and asked him to stop using their plug.
From article 1 of 2 above:
Kamooneh had taken the liberty of charging the electric car with an exterior outlet at the school. Within minutes of plugging in the car, he says a Chamblee police officer appeared.
"He said that he was going to charge me with theft by taking because I was taking power, electricity from the school," Kamooneh said.
From article 2 of 2 above:
Kaveh Kamooneh plugged an extension cable from his Nissan Leaf into a 110-volt external outlet at Chamblee Middle School while his son was practicing tennis. A short time later, he noticed someone in his car and went to investigate—and found that the man was a Chamblee police officer. "He informed me he was about to arrest me, or at least charge me, for electrical theft," Kamooneh told Atlanta's Channel 11 News.
I noticed that the events leading up to the arrest are different in the two stories. The first one states that he was approached shortly after plugging it in and the second one states that he caught the officer searching his car. Which one is accurate? Both stories quote Kaveh Kamooneh.
There is a third possible scenario that the officer asked the guy to unplug the cord, the guy acted like an ass and the officer waited to confirm with the school board that the guy didn't have permission to use the outlet prior to making the arrest. You never see anyone admitting that they did something wrong to the reporters.
They could even post a sign saying "please do not use our plugs to charge your devices." .
So you believe that unless you are specifically told to not do something you are free to do as you want?