It's clear Jim has every right to take that DRM-protected shopping cart home. After all, by only purchasing a fixed number of carts and then restricting their departure from the parking lot, the supermarket owner is clearly creating an artificial scarcity. Recognizing this consumer-harming power of the supermarket owner, Jim has every right to balance that power in favor of the consumer by defining the act of taking the cart as fair use. Let's see how he does on the four fair use prongs that stemmed from the Sony decision.

1. Purpose or character of use. Well, Jim's use is both noncommercial and personal, so I think he's got that one nailed.
2. Nature of use. This is harder to translate, but Jim isn't attempting to republish, or take any credit for, the existence of this cart. Passes here too.
3. Amount of work used. Okay, he's using the whole cart, wheels and all. But that cart is identical to hundreds of other carts in the lot. Viewed collectively, Jim's use of "shopping market cart" is quite minimal.
4. Effect on market. This is a no-brainer. No one is going to notice the missing cart, and it certainly won't impact the "supermarket." As for the market for manufacturing carts, this could trigger the supermarket to order another cart, thus generating more sales.

So Jim, take that cart, and try not to think about what might happen if everyone followed your logic.