The optics on the policy at Sam's isn't great either, but at least there is some possibility they'd get lucky and catch someone. Both are more about deterrent than catching anyone, obviously. But, at Sam's most items are in your cart, not bagged and they scan an item or two with the receipt. So, theoretically they could find an item in the cart that wasn't paid for. Walmart, at least in my limited experience, just eyeballs the receipt and your cart - which probably contains bagged/hidden items anyway.
Either way they send everyone out with a 'are you a thief' message.
While I hate going to Walmart, and everything about it puts me in a bad mood. This is no reason to take it out on some poor door greeter. This is Oklahoma, we haven't forgotten how to be nice to each other.
As goofy as this may seem, I agree with both of these posts.