If you own a business and you invite people to come spend their money at your business, you're required to protect those people from reasonably foreseeable hazards on business property--even if those hazards are caused by third parties.

Wal-Mart didn't do that. The store managers should have known that their big sale would attract crowds waiting for the store to open--that's what Wal-Mart wanted and that's why they spent the big bucks on advertising. So they should have hired enough security people to restrain the crowds and get them through the doors in an orderly fashion.

No one should "expect" to be seriously injured when he or she responds to an advertised event at a business. We should expect businesses to conduct such events in an safe and orderly fashion.