Probably because they are the symbol of what's wrong with America today...?
Greed over worker's rights... Corporatism run amuck... Total lack of loyalty to its US suppliers...who provide a customer base for Walmart.
As America self destructs in this final daze of the greed and looting orgy by the elites...Walmart will suffer most from "What Comes Next."
And it won't be a pretty picture unless Walmart gets right with America and the American economy....ASAP.