“There’s no such thing as a free lunch,” goes an old saying. I’m not sure I can agree that it’s strictly true, but it’s still wise advice. We seldom get something for nothing, but people often let themselves be suckered into thinking that someone, often an anonymous stranger, really is giving them free stuff. It’s true that humans can be and often are altruistic and help each other, but that seldom occurs between strangers or between businesses and people.
The “Free Lunch” flag takes many forms, some of which are kind of subtle, some not so much. For example, there are sites that let you play “free” games on the internet. Now, granted, some of these are amateur games that really are being shared free of charge. Mostly, though, something is driving the business model. Often, it’s advertising for either the games’ creator or a third party. This may be an acceptable price to pay to you, in which case: have at it. But remember that there is a price.
More subtle examples of free lunches abound, however. Consider customer loyalty cards. You get discounts (often) for using them, but is that really something for nothing? Nope. Generally, stores are collecting data on your shopping in exchange for the discounts. Again, it might be worth it (the data is usually used only in aggregate, they don’t care about your purchasing patterns particularly), but it’s a price none-the-less.
In the end, the free-lunch problem doesn’t mean that we should refuse offers that look good. But it does mean that anytime we hear about something that sounds too good to be true, we should think about the details and what the (often hidden) costs might be.