I always like to attribute many things we do at work to a real life example elsewhere, say at home.
Let’s consider that you order a pizza for your family at home. You give your requirement, your contact information and pay for the delivery either upfront or when the delivery takes place.
From the moment you order the pizza, your patience has a limit of waiting for the delivery boy. Perhaps half an hour, or an hour after which you will begin to consider what to do next. So finally the pizza boy comes in and hands over a pizza. You are smiling, your family is happy and you are feeling great that you got what you ordered.
But just then you notice that you have got a 9 inch pizza instead of a 12 inch one. You ordered a panneer pizza (veg), but you got a pepperoni pizza (non-veg). And the boy arrived an hour and a half late so your pizza is cold and not edible anymore. You are seething with anger and decide to cancel your order. For good reasons. The delivery did not meet your requirements.
This example is somewhat a simple one, but brings about the fundamental things that one would like to expect while committing to a job for delivery.