Do you think they ever intended to let the men go?
Spoilers...
There are elements of the two men who are building the wall being the other two men's playthings. It's all a game to the rich, and not even a eal important one -- they never come to the field once to see the progress. I don't think they ever had any intention of letting these two men ever leave. Do you?
Who do you think beat up Pozzi? (I think it was the caretaker.) Do you think they ever really took him to the hospital? (I don't.)
Do you think there are messages here about society... about how the rich take advantage of the poor, about how not to reach above your status, etc? And about how status is the luck of the draw?
That's what I see.