A number of years ago my son worked in subway for a while.
When you order a 'sandwich' with various fillings the fillings have to be loaded in a certain order. For example, if you wanted tuna mayo with sweetcorn and onions each filling had to be placed in the 'sandwich' in the correct order as designated by subway. If a supervisor spotted a counter assistant doing it wrong the whole lot was thrown in the bin and they had to start again and do it correctly.
He said the wastage was horrendous and it didn't matter if the customer wanted a particular piece of filling put on first. If it wasn't in line with subways order then it was done.
