Not sure what's so surprising/interesting about this (I don't have a subscription to read the full article). This nugget in the introduction seems to summarize the tech behind this --
> Sensors installed in electric bays can be used to detect the presence of a vehicle and whether it is being used to recharge the car battery.
> Sensors installed in electric bays can be used to detect the presence of a vehicle and whether it is being used to recharge the car battery.