If you use google and look up Wal-Mart versus Costco, you will find a number of articles comparing the too.
Short answers to your questions:
1. About 13 percent of Costco's employees are unionized.
2. Costco employees are paid more than average in the retail industry, including more than at Wal-Mart.
3. Costco's health care eligibility requirements for health care are more generous than Wal-Mart's. Specifically, Costco employees become eligible for health insurance after three months working full time, or six months part time. At Wal-Mart, many who work full time must wait six months to become eligible. Part-time workers are not eligible for at least two years. Because of turnover, some employees never work long enough to become eligible. (http://www.brynmawr.edu/admissions/careers/abelson_story2.htm)
Costco has even been criticized by Wall Street analysts for being so generous to its employees. One analyst quipped a few years ago that it was better to be an employee at Costco than to be a shareholder of Costco stock.
As time has passed, however, these criticisms have disappeared. Why? Compare stock performance.
Five years ago, Wal-Mart stock was trading at roughly $52 a share. Today, it's at about $46 a share. If you'd invested $1,000 dollars in Wal-Mart five years ago, you would have lost about $115 dollars.
Five years ago, Costco stock was trading at roughly $35 a share. Today, it's at about $54 a share. If you'd invested $1,000 in Costco five years ago you would have gained about $543.
That's why you don't hear as much criticism of Costco's employee compensation program these days from Wall Street.
Thanks for the info. I'll have to do some googling later on.