I think that walm might have been pointing out that the photo doesn't show that, it just shows a guy in a cab who could have been anywhere - it doesn't show he was driving at the time. I don't think he was doubting what you'd said, just that the photo doesn't support it.
If you look through the cab there is a 'Controlled Zone' road sign that you find at the side of the road which suggests the truck is across a road junction an thus very unlikely to be parked.
If you look through the cab there is a 'Controlled Zone' road sign that you find at the side of the road which suggests the truck is across a road junction an thus very unlikely to be parked.