"Working for a retail chain doing shop fit out and maintenance. I visited stores in various places and had some interesting experiences with "stock"."
In my youth, and possibly for my future sins as kama works in strange and non-euclidian ways, I worked in the warehouse of a now defunct local supermarket chain. The stock control system had almost exactly the flaws you describe and it was indeed seen as a perk of the job and compensation for low pay and crap hours.
That was until someone discovered a bug that generated spurious stock movements, the judicious application of which could make stock vanish on command. Cue a sudden spike in "shrinkage and spoilage" but only on the most expensive lines. I suspect the last straw was when cartons of cigarettes started disappearing...
The front end staff got an interview with Mr Plod and a few were "let go" extremely sharpish. Fortunately I was in the warehouse and thus above suspicion. I have no idea why - the stores were the source of all serious pilfering. So we quietly got on with our games of under counting (to ensure a supply of snacks and drinks) or over counting (to generate errors that could be reported with much indignation while covering up more serious stock take discrepancies)