Walmart isn't the only big retailer installing a slew of EV chargers in its parking lots. Target and a collection of retail property owners (PDF) have unveiled plans to add a horde of charging stations in the (relatively) near future. In Target's case, it's adding chargers at more than 100 locations (600 parking spaces in total) over two years with the help of a variety of backers, including Tesla, VW's Electrify America and ChargePoint. The big-box store only has chargers at 18 locations out of 1,800-plus as we write this, so it's no trivial expansion.
The other companies, meanwhile, are working with Electrify America to install chargers at more than 100 "retail, convenience and refueling" locations across the US, including Target's. They'll range from ordinary 50kW chargers to 150kW in urban areas and 350kW along highways. Those last two charging levels will require cutting edge EVs, of course. All of the stations should either be active or under construction by June 2019.
In both cases, the goal is the same: retailers want to both help the environment and (crucially for them) draw you to their stores with the promise of more electricity. If you have your choice of stores, you may be more likely to visit the ones that let you recharge while you're busy shopping. Not that this strategy is necessarily a problem. Many chargers still tend to be limited to dedicated stations -- this could be helpful if you'd rather not go out of your way just to plug in.