I have done Wal*Mart, and agree that it is less than ideal.
But now, you are not permitted to scan your own items. It is required that an employee do it. The downside is thar even on heavy days,not more than four or five stations have employees assigned, with the rest being shut down, and one long line for customers trying to use it.
No cash allowed, but often, someone's card doesn't work and that station is held up until a supervisor is called and the problem straightened out and the station back in use.
Clearly, the cost of highly-paid employee interfacing of all the stations is more than the management can afford to add to the general price of the products without pressure from the customers.
I think the reason this outflow is throttled is because of some kind of thievery incident to the use of self-scanning schemes to defeat the purpose of them.
It is true that a lot of the customer population is from classes of people who are of foreign cultures or tenement areas, to put it mildly.
It appears that there is some restraint on the kind of shoppers use the store because in the BJ clubs you at least have to pay yearly for a membership card to be cruising the store and buying items. But not in Walmarts.