As someone who has spent some formative years going to Waffle House and been to WaHos in 8 different states, it plays a big role in Southern culture (especially in Atlanta). Would I say necessarily they're playing off the whole Wal-Mart strategy? Likely not, that's more of an Applebee's thing to do. Applebee's tends to have locations near Home Depot, Lowe's, and Wal-Mart.
Waffle House is a real estate company masquerading as a restaurant, but so are many restaurant chains. Real estate location is EVERYTHING with chain restaurants. The objective is to be near areas off interstates where travelers would pull over and in the case of Waffle House, the late night crowd really generates a lot of revenue and being in the vicinity of the outflow of bar traffic is a must. Ever seen security or lines outside of a Waffle House? You'll find them between midnight and 5 am when the bar traffic has made their way to try to help the weary avoid a hangover the next morning. It's an environment that has a mingling effect among customers unlike other diner or restaurant experiences.
The sheer ubiquity and low cost of real estate plays a massive role in the success of a location. Also, Waffle House locations are small generally uniform lots with buildings, unlike other sit-down restaurants that do not serve alcohol. They're competing with Perkins', Denny's, Huddle House, and IHOP for market share. Their competition have less ubiquity, but they take up more space. The margins are much lower and to compete and survive, cost-effectiveness is a must. In the case of Waffle House staff, the pay is not good, but drunk people tipping cash does go a long way.
The experience at Waffle House is unique and almost impossible to copy as every part of the way you order there is built around efficiency, transparency, and a lack of formality. Waffle House fills the gap where Greek immigrant restauranteurs who established diners did not pursue (largely the American South) and made a no-frills, sit yourself down sort of environment.
Hopefully, I have smothered, covered, and capped this post in a way that is not scattered.