> But you can't just charge random amounts post factum without the person having any idea why they suddenly owe those amounts. Is it actually different from pa

> But you can't just charge random amounts post factum without the person having any idea why they suddenly owe those amounts. Is it actually different from paying a contractor to do some work for you on an hourly basis, and them then having to "think more" and thus spend more hours on problem A than probably B?