Well in the Soviet case, plumbing and cheese are most certainly not privately held resources. Doing such work as a plumber means you're essentially acting as self-employed or a business, which is illegal. The cheese is probably produced on a collective farm and sold at a state-owned store.

But surely the cheese case would not be okay even in a Western capitalist context where the store is privately owned. Just replace it with a more scarce product. A store employee isn't allowed to tell customers the store is out of iPhones while keeping a dozen stashed for preferred buyers.