First off, I disagree with your statement that Wal-Mart has bad business practices.  They are a great company.

However, the fact is that you are just not aware of the public "outbursts" against Wal-Mart.  There is A LOT.  Possibly more than Microsoft.  They happen to be diffferent issues.  Pay attention to politics and you'll hear a lot about Wal-Mart.