You are welcome to obligue their request, however if the law states, as it does, and as it should, that a store may not force you to do so, then you and the store need to respect the rights of folks who choose not to obligue their request.
I am sure I can find someone who thinks subjecting your child to a full cavity search at school when there is a suspicion of drug activity in the school is a reasonable request.. Just because you find something reasonable does not mean that A) it is, or that B) others should be subject to what you consider reasonable.
The law is the law, if Wal Mart detains people unlawfully they are violating the LAW. Period. Wal Mart nor any other company has the right to violate the law.
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.
No one has said anything about unlawful detention (except the website I referred to at the beginning of this debate).