Depends heavily on the operator, but the “wholesale” line is often more story than fact. Most independent carts buy through the same or similar regional produce distributors that supply small bodegas and independent greengrocers, but they don’t have the same cold storage or turnover volume as a supermarket. That means three things.
First, carts are best for high-turnover items you plan to use the same day or next day: leafy herbs, chilies, citrus, avocados if you know how to pick them, and seasonally fragile fruit. Those are the categories where the cart can beat a chain on quality because the produce hasn’t been sitting in a refrigerated back room for days.
Second, supermarkets tend to win on staple vegetables, especially when they run weekly specials. If you’re cooking broccoli, onions, potatoes, carrots, or salad greens for more than one meal, the price per pound and shelf life at a store usually beat the cart.
Third, the exception is household size. For a single person, buying two carrots, one onion, and a small bunch of parsley at a cart can be cheaper in total than buying whole bags of each at the supermarket and tossing half of it. That’s not the same as cheaper per pound.
We split it: one supermarket trip on Saturday, then a cart run on 30th Ave for herbs, limes, and the occasional emergency vegetable. I would not use one for a full weekly shop.