Yesterday I noted how Americans tend to overestimate the amount of profit earned by corporations. The actual profit margins are so thin that, as Mark J. Perry points out, for the pany all sales revenue from January 1 to December 7 would go to cover the firm’s expenses for the year, and its sales on roughly the last 24 days of December from December 8 to December 31 would represent its profits.

For the other industries displayed in the table above that operate on thin profit margins of less than panies in those industries have to operate until the middle of December (airlines for example at December 18), or even until the last week (department stores), or in the case of grocery stores until the middle of the last week of December. Think about it — a grocery chain like Safeway or Kroger has to operate from January 1 to December 26 until it breaks even for the year, and only then will its sales revenue from the the last 4.4 days starting on December 27 represent the profits for the entire year! And that’s only if everything goes exactly right, and nothing goes wrong — like a sales slump from a recessionary slowdown or from petition from a petitor like Walmart and Target (now in the grocery business); or like an unexpected increase in costs that can’t be passed along in the form of higher prices, etc.

As a percentage of operating costs, profits are often miniscule. Yet they play an outsized moral role in the creation and distribution of goods and services. “Profits motivate people to work hard for themselves and to make life bette for others,” says economist Walter Williams.