Last year we looked at the Shoppa, a personal shopping cart from Australia. The idea is that you own one and use it door-to-door, rather than using the supermarket's carts.
This Clax Trolley, a fold-flat utility cart from Holland, is not designed specifically for shopping, but I think it could easily serve the same function:
Here's how it breaks down. I dig that even the basket collapses flat:
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I'm also digging that you can fold the cart flat with the wheels on, or super-flat by removing the wheels. That wouldn't make sense to do every time, but I like that they've provided the option. And while the Clax doesn't look sturdy enough for outdoor rural use, I could see it providing good utility in an urban environment.