Costco and Walmart are not direct competitors. If you want to compare Walmart's wages/benefits do so with Target and Kmart not Cotsco.
Also, why do you pick 5 years ago to start looking at stock price? How about 20 years? How did Wal-Mart investors do over a 20 year period?
Look at this chart to see how misleading your 5 year comparison is:
http://finance.yahoo.com/q/bc?t=my&s=WMT&l=on&z=m&q=l&c=cost
Perhaps your reply should be to 3catsanadog. That's who brought up the Wal-Mart/Costco questions.
And, well, I didn't choose 20 years because Costco wasn't publicly traded 20 years ago. Five years is a long time in the stock market. It was an arbitrary pick. I could have picked one year.