After the last gun shop I worked for went belly up I took a job at the local walmart. Working the sports counter I would have to say that walmarts training programs are a joke and it is no surprise to see the litany of complaints about people who don't know anything about what they are selling.
That is part of the problem that they try to address by requiring ID for all kinds of purchases and they program it into the computer registers. They are a large, lawyer heavy corporation and deathly afraid of violating Federal, State or Local laws when selling anything that might be age restricted. Too much afraid of lawsuits and bad media but they don't want to miss out on any potential money stream either.
The current program for ammo sales requires entering the customers birth date, now it's pretty obvious that some people are more than old enough to buy any ammo they want but the computer won't let the sale proceed without a date so one must be entered. As to scanning an ID, never heard any such thing but some areas might be considering it (or someone was passing on corporate rumor, I've heard some pretty stupid things myself from employees). Walmart in this area sells basic shooting ammo in popular calibers and they are cheap. Hard to compete with in a society where price is seemingly the most important thing. A shop I was with years ago had the misfortune to have a Walmart @ a mile away and to compete for basic target ammo sales we carried a lot of off brands, sold bulk and surplus ammo to get a share of that market which is a vital, daily income stream (gun profit margins are small, ammo accessories and services are what keeps small shops open) and without enough of that the "out of business" signs go up.