Suppose someone has voluntarily gave up onion and garlic. Now he went to a restaurant which also offers no onion and garlic food. So you order food without onion and garlic. Mistakenly restaurant served you food with onion and garlic in it. Now if you complain then food will go to waste and chef will pay for the wastage from his salary and if you eat that then you will feel sinful. What is the right path? Insult food by letting it go waste or go against your belief of not eating onion and garlic. Person can choose to pay and not eat but even then food will be wasted.