I don't shop at Wal-Mart because of their Union busting but last time I went to Costco there were a handful of "floor" employees wandering around to be found if you needed help. Costco pays its employees well because their CEO thinks happy employees lead to better workers[1]. In fact the last big box store I shopped at which was Home Depot had less people around to help than Costco. I realize that's anecdotal but you can't write down high employee salaries as "Being just a wholesaler".
It is, for all intents and purposes, a wholesaler. They sell things in bulk. That's their thing. And they don't hold your hand while doing it.
There are no friendly people walking the isles willing to direct you, just cashiers. You pay for access. They only take AmEx, etc.
Mind you, I love the place, but it is the way it is because of what it is, not because it cares.