Is the school the one his kid goes to? Then I see nothing wrong with him having it plugged in. He does pay the school for his son to go there and use the facilities. Can they now arrest teachers and students for plugging in a phone charger into the outlets? Where is it written saying that you can't use them?
I don't see the gas station example as being the same. Everybody knows you have to pay for the gas, that is the whole point of the gas station and they are set up to receive payment for the gas.
Cell phone chargers: Inside, they are implied consent for employees and customers (students and visitors). Absent explicit rules, power outlets are implied consent just like a drinking fountain is implied consent to all those who come by and see it.
Outside outlets are for groundspeople to plug in a weedwhacker or various tools to support the facility. They aren't there for vagabonds to plug in their laptops and cell phones, any more than they are there for parked cars to charge. Absent a sign indicating that a particular parking stall is intended for electric vehicle charging, none of the stalls are intended as such.
How would you feel if some guy parked on the street in front of your house, walked up to one of your strings of Christmas lights, plugged his car into the socket at the end of the string, and started charging his car off your power system?
Think about it: You're talking about enough electricity to convert into 100+ horsepower, to move a vehicle. That's orders of magnitude more current (i.e. $$$) than a cell phone charger. Would you plug into the side of Walmart when visiting there? How about stopping at Chevron... plugging your car in at the gas station and not buying any gas? You're gonna start spinning that meter on the side of the building pretty dramatically.
Then, there's the circuit design considerations. How many amps does a car charger draw at 120v? I'd guess it is somewhere around 10-15 amps. If the circuit has multiple outlets and it's only designed for conventional outdoor groundskeeping electrical purposes, then it's not intended to have a car plus additional load. Let's say another guy comes along, equally inconsiderate and oblivious, and plugs in HIS car, too. Now you've popped the breaker. Now the groundskeeper has to stop working, figure out why the electricity has shut off, deal with a couple of obliviots that have popped his breaker, correct teh stoopidz, and turn the breaker back on.
You want to own an electric vehicle? Great. Go for it. Knock yourself out.
But don't start stealing electricity from everyone else in the process, thinking you are somehow going to get "free gas" out of the deal. Or start ruining people's days by popping breakers, running 100ft extension cords in places that can't handle that long of a run, or other irresponsible bullscat.
Most buildings are NOT designed to handle car charging.
Doing what this guy is doing, is on par with seeing the school groundskeeper out on the riding lawnmower, wandering into his maintenance shed and taking one of his 5 gallon jerry cans of gas.