Well, since there are no "rules" posted and I apparently fall into one of the "do not screw with" profiles (because profiling is how they decide who to ask), it's apparently against the rules to check my receipt, so sure, I'll go to Walmart. Never seen one at Lowes, never been in a Sam's.
See how asinine that all was? When it's not a specified rule, has no enforcement, isn't reinforced by actual LEO or even paid security, is based on profiling (so as to only harass normal looking folks), is only present sometimes, and isn't even applied to actual thieves who can decline said search, it really isn't anything but the window dressing of loss prevention.
Imagine if you bought a shotgun from my wife inside my house while I watched, but before you stepped out of the door, I asked for verification that you actually paid her, and instead, you told me to "piss up a rope", and I smiled and said, "have a good day, sir" as you flipped me off and walked out the door to absolutely no consequence. This is receipt checking. It's a Mobius strip of asinine and arbitrary to the nth degree of Kafka-esque surrealism.