I doubt many states have laws forcing retailers to allow people to take stolen merchandise out of their stores.
I personally don't like paying for the theft of others through higher prices, so I welcome reasonable attempts to limit theft. Checking the receipt on the way out is, in my opinion, quite reasonable.
I also don't mind when a retailer checks my picture id when I use a charge card... because I have enough brain cells to understand the need for it and the cost of NOT checking.
What you consider reasonable, does not make it legal.
You don’t like paying for theft? Well guess what you need to stop purchasing anything everywhere.. all business involves theft.. its called shrinkage. A company’s desire to minimize shrinkage does NOT give it the right to break the law.
As to the retailer checking your ID to use your credit card, this has nothing to do with the law. They are not violating any law by asking you to prove who you are when using your credit card... in fact the Credit Card Company, (not you) actually own that piece of plastic, and set the rules by which it can be used, and they can cut off your or a merchant at any time from their systems if they so choose.
So you are comparing apples with oranges.
Wal Mart greeters have the right to ASK to see your receipt, they do not have the right to force you to provide it. You choose to obligue that is your right, other choose not to, that is their right.
I am not saying you cannot continue to happily obligue the requests of the Wal Mart greeter, however they have no right to prevent you from leaving the store with your property.. and refusing to let them look at your receipt is NOT evidence of theft.. Wal Mart has shelled out payments for detaining people over this crap, and will continue to do so because it is ILLEGAL.
Once you have paid for something, it is legally YOURS. You have no more legal obligation to show proof of that ownership to the Greeter at the door, than to any other person walking down the street. And they have no more right to DEMAND that you show it before being allowed to leave. Once you have paid for something it is yours, period. A retailer has no more right to demand you provide the receipt before you leave, then they do to come to your house and demand you provide proof you own the lawn mower that is in your garage.
The law is the law, and businesses must operate within the law.