I have read many articles on WalMart’s use of data mining - they are even hiring in Silicon Valley about this. I know they were pushing for RF tags, I know they have figured out which items get sold together during snow storms (shovels and hot chocolate IIRC). That is not proof that they spend all this money on greeters for a reason - but it is hardly an unsupported hypothesis. WalMart may be evil, but they aren’t dumb.
First, that’s not the kind of thing they’d feel compelled to cough up in the annual statement or otherwise publish.
Second, even if it’s just a touchy-feely exercise of employing old folks and mentally disabled folks to grin and say hello, they clearly feel that they derive some benefit from it- whether it’s goodwill in the community, making the shopping experience more pleasant, or something else (shoplifting prevention?), or they wouldn’t do it at all.
Personally, I suspect it’s some combination of all of the above; it’s an easy way to look more socially conscious by pointedly employing underemployed demographics, a way to easily cut down on shoplifting (we presume), and something that might make their customers have a slightly more pleasant experience in their store.
But, like I said before, it’s a pretty easy data mining exercise to determine if the presence of greeters either reduces shoplifting or increases sales (through pleasant experiences).
Somebody thinks they are needed, why do you think they are hired?