Eventually, the only thing that is left is Wal-Mart, and the people have no choice left but to shop there. This can cause an effect similar to a monopoly in a small town. People may have no stores for miles except for Wal-Mart because ever place has had to close because it couldn't compete with Wal-Mart. This then leaves people with no choice BUT to shop at Wal-Mart, and this only continues the vicious cycle elsewhere in other small towns.
This can cause devastation effects on a town's economy. Wal-Mart then becomes the ONLY major player still in the economy of a town. This not only puts small stores out of jobs, but gets rid of the basis for all business, competition. This can then lead to Wal-Mart business policies becoming lax, as they no longer have to compete and now are the only game in town. The entire point of business is to have competition, but Wal-Mart makes sure to destroy all competition it can have early on.
Wal-Mart also has many problems that go deeper than just the problems after the store comes in. If everybody who shopped at Wal-Mart sat down and watched this movie about how bad Wal-Mart treats its employees, and the poor wages that the corporation tries to pass by. Examples are given of major sexism against women, and how unfairly the Wal-Mart Corporation treats women.