I feel that they are not prosecuting you because they are ashamed that they were taken that easily. They want to keep it hush hush so other employees dont get the same idea BUT IMPROVE ON IT.
That was my inkling. Unlike the other gift card scams I saw described, this one seems much harder to circumvent. It's interesting if they weren't ready to prosecute you even when they thought you were doing it differently.
I looked into 'walmart employee coupon theft' and found way in the back a
single report dealing with theft by coupons, although she was using unauthorized coupons, which is just stupid. There was, however, a couple pages back,
a book on organizational behavior which mentions on pages 151-152 that during a single promotional campaign, 12.5% of Wal-mart employees engaged in this scam, costing Wal-mart $700,000! The only other references to 'coupon fraud' were in studies, such as the book above.
Clearly, Wal-mart doesn't want this kind of scam to be any more widespread than it is. I think they got no way to fix it.
Next time you're talking to your Wal-mart lady, mention that the biggest paper in your area is doing a big report on growing employee theft, and somehow they got your name and they want you to explain how you did your ditty. See how she reacts to that.