WalMart: License to Kill?

Has anyone else been paying attention to the Escalating number of people WalMart security guards have killed in the last several weeks for shoplifting offenses? There's another one in the news today, and it seems like there have been a dozen or so executed on the spot by WalMart security guards since Black Friday.

http://www.dailymail.co.uk/news/article-2245074/Walmart-security-guard-shoots-shoplifting-mother-dead-parking-lot-tries-escape-young-children.html

Why is this being allowed to continue with impunity? Since when do we allow corporations to summarily play cop, judge, jury and executioner for misdemeanor offenses with nary a peep of public outrage?