I can guarantee you 5x the worth of those goods he was carrying was already stolen that day. 

If he used self-checkout, it would be entirely possible for him, or anyone else, to have stolen something.

I have no issue with presenting my receipt, in fact, I offer it to the person at the door as a courtesy, sometimes they look at it, sometimes they don't.  If you've ever been a retailer, as I have, you'll know that shoplifting is a serious problem, and you will have people who just saunter out the door with items.  There are some people who view it almost as an entitlement.

true, I don't mind giving a receipt for a gaggle of goods. But I rarely go to Walley-world, anyway.

I went to Walmart on Saturday afternoon, had to offer it up. I find receipt checking intrusive and offensive. They assume I’m a thief. 
It has become an exercise in futility. While the security guy was checking to make sure I paid for the two gallons of white vinegar, four bags of cat litter, and value pack of Little Friskies, (chicken chunks with extra gravy), ten others could have disappeared into the parking lot with thousands of dollars of stolen merchandise.  

I went to Walmart on Saturday afternoon, had to offer it up. I find receipt checking intrusive and offensive. They assume I’m a thief.
It has become an exercise in futility. While the security guy was checking to make sure I paid for the two gallons of white vinegar, four bags of cat litter, and value pack of Little Friskies, (chicken chunks with extra gravy), ten others could have disappeared into the parking lot with thousands of dollars of stolen merchandise. 

A retailer always has to assume that a customer is a potential thief.  That said, some people "telegraph" this more by their furtiveness and peculiar behavior than do others.  But if you don't treat everyone alike, well, that grinds some people's gears.  (Or even if you do.  Damned if you do, damned if you don't.)

And some customers, even those without criminal intent, are just itching for a confrontation, so that they can make some kind of statement, and paint you, the shopkeeper, as the bad guy, and possibly even further some kind of agenda they've got, or cater to some kind of entitlement on their part.

I've been a retail manager.  I know.