I think the rule is that, when a business charges a consumer a penalty fee of any kind, the fee must relate to actual costs that the customer's actions imposed on the business. A business could estimate the cost of bananas, but they couldn't use the sale price if that was usually ten times the cost. This applies to things like bank overdraft fees and hotel cleaning charges as well. The idea is that consumer contracts can recover costs, but aren't allowed to punish people.

I don't have a source for that.

Wait til they apply music piracy concepts!

"sir, you ate 4 grapes in store. Our grapes average 2seeds/grape, so we've calculated lost sales in the range of $800.

You see, those seeds could each grow into a vine that will produce an estimated $100 worth of grapes over the lifetime of the plant. You're basically stealing that money from us!"

I may be wrong... I read this previously that was very clear about the customer was due to pay the supplier cost. But I did a google now to find the article and the best I could find is this is a civil case and not "not covered by the Australian Consumer Law" and it seems to be at discretion of the court for value lost and how at fault you were.

https://www.consumer.vic.gov.au/shopping/refunds-and-returns...

I thought "cost" was one of the simpler concepts - the price at which the store bought the item from the supplier.

Even that fluctuates frequently. When I worked at a grocery store, when you ordered something it would show you what the item would "cost" the store.

This could change from day to day (e.g. fruits, veggies), vary based on quantity ordered, etc.

Then you get into private label (store brand) products, where the "cost" was usually either $0 or some ridiculously low number.

This was a national chain. At the store level at least, we wouldn't have been able to find the value of an item "at cost" with any confidence.