Lets say you go into Wendy's but you are going there for a coffee, instead of the burrito. You are paying full price for that coffee. The cashier then says that you have try the free burrito because they bought one. Nothing extra is coming out of the consumer's pocket.
Yes, Wendy's will try to help pay for the cost of the burrito by eating the profit that they would have received on the drink, but that doesn't mean that the burrito isn't free to the consumer. It means that the profit margin for Wendys will be changed. I don't think that anyone is debating that the preparation of the burrito costs Wendy's something.
:dcr:
Then that guy walking in there would have lucked out and got an additional burrito at the cost of his coffee. However he had to buy the coffee to get offered that. So it still isnt free.