So why can't websites, do like any other "store". They can make you agree to pay for something but not enforce payment. Like couldn't I say, here's my article. If you read it you agree to pay me $1. Now a lot of people might read it and it might not be worth my time to go and collect $1 from each of them, just like Walmart isn't going to tackle you about eating a grape in the produce aisle. But if you want to make a business that's about exploiting Walmart's non-enforcement of free grapes then they are going to stop you.