A Brilliant Idea
It was not a big deal for the foreman as long as they are no longer there when they are expecting deliveries. The foreman just specifically needs those slots when the delivery trucks are in the area. Where else can they park those big trucks, right? It will be an obstruction if they do not have a reserved spot waiting for the trucks. It will cause traffic jams as well.
Boxed In
Every time that a delivery is on its way, the foreman will request the parents to move their vehicles. After all, they are parking in a no-parking zone, so most of the time, the drivers will no longer argue and just move their cars. He was not very strict about cars parking in that zone, and he would courteously request the parents to secure another slot.