Ratatouille famously did this, with actual scene elements rather than digital watermarking.
There's a scene with a poster in the background. Every copy of the movie had different digits on the poster, I think with a unique ID for each cinema they were sent to. When a leak came out they could check the ID and know exactly which avenue it was leaked from.
So the people carrying less items of smaller size have an easier time, and the person carrying the larger items to go in the larger truck have to go further away?
Ah yes, logic.
Why not have large parking spaces near the front to accommodate this, not expect people to just park somewhere else.