years ago i worked for a major big box retailer in corporate. 1000+ stores.

Our number one and 2 stores, by both revenue and profit, by a longshot, were in Paramus, and not even a mile apart (not in the malls either).

Really opening on sunday would just have spread things out, and carry the burden of the cost of being open an extra day. Not to mention poach some business from neighboring counties where people who HAD to get something on sunday would go.