With their business model, Wal*Mart must have thin margins, it wouldn’t take much to push them into unprofitability in many of their stores.
Some stores, I am sure, are very profitable, others less so. With pressure on them to raise wages, closing couple of their less profitable stores puts pressure on politicians and unions who like to use them for a punching bag.
If you’re margins are thin, than you have to have high volume to have high profits. $1,000,000 might sound like a lot of profit, and it would be if some small bakery could make that, but it might be a very thin one for a large Wal-Mart with the amount of business it does.