> These questions are fundamental to correct billing at any kind of scale, and the answers are not simple As someone who also works in billing and subscription

> These questions are fundamental to correct billing at any kind of scale, and the answers are not simple As someone who also works in billing and subscription management, I 100% agree with everything you said and want to add an extra thing: Even when the answers ARE simple, there's so many of them that you end up realising you want to pay someone else to make it their problem instead.