Allow dollar based discounts on items, not just transactions

[SBCB]

I own a coffee shop that provides a $0.25 discount if customers bring their own cups or mugs. Since this is a dollar based discount, I can only apply it once per transaction. But if they bring in multiple cups/mugs for multiple beverages then I would like to apply the discount to each item ordered (or multiple times on the transaction). This is only one example of where this feature would be useful. We also give $1 off drinks to workers at nearby businesses. Sometimes they will come and order multiple drinks on a company card but I am not able to apply the discount for more than one drink.

I don't understand why percentage based discounts can be applied on items and transactions but dollar based discounts are limited to transactions only.

Online suggestions mention making the dollar based discount automatic, but there is no way to automate whether or not someone brings in a cup/mug. It only makes sense as a manually applied discount.