Hi Gareth. Your started this thread while I was in hospital after a workplace accident, so this is the first time I have seen it. I can;t help with pictures at the moment, but the types of set-ups you are wishing discuss aren't totally unusual in history of various places.
I have seen three-wheel types at work in strawberry farms, working along weeding the crop, and likely also undergoing harvesting. In Europe, it is not unusual to see work bikes and trikes being pedaled into market areas or home again; this applies mostly, I think, to large areas have virtually no access permitted for vehicles. They also ara not completely foreign in Australian marketing situation.
The type of bike you show in the pictures, bit without the overhead rails, if a little familiar, although the soft drink and ice cream seller have a less wide front to accommodate their big boxes, and to ensure they have easy access for customer service.