How it happens is easy-how it gets "delivered" to the customer is another matter-especially if there was an AHJ inspector involved.
Consider that making up receptacles is a tedious job in an uncomfortable position-and in theory the jouneyman/experienced crew member should be able to show the newbie once and keep him busy for some time-so the newbie (first day as an electrician?) gets the task while the experienced guy makes up switches, etc.
We all know we need to check up on the newbie-but how many of us get busy and forget follow up? I'm not excusing it-it should have been checked.