How many of those have you seen in the US?
None, because noone wants to bike 5 miles for 3 bags of groceries.
You moved the goalposts, but that also brings up another problem in the US: land use that forcibly segregates different things - like making corner stores illegal in newer suburban developments.
Maybe a dozen or so? But if you only have 3 bags of groceries you can just use a regular bike + basket.
We’ve moved the goalposts from “Food, beer, and cat litter would be too heavy for a bike.”
Also, my grocery stores are 0.7, 1.1, and 1.6 miles away, not that it matters. 5 miles is just not very much time at 20-28 mph. I think theft and weather/comfort are bigger obstacles to most people than distance.
IMO you don't see them in the US because they look, frankly, dorky to an American aesthetic.
I see loads of those around my neighborhood, usually ferrying kids.
At the same time, I don't need to go 5 miles for groceries, so you might be picturing using a cargo bike in sparse suburbs. If your built environment is car centric then almost definitionally using any other mode of locomotion is going to be subpar.