That makes no sense. If there are complications and the delivery is delayed, then they get 5 stars for getting it to you? How do you know what complications or difficulties they ran into? All you're gonna see is delayed package, and by your scale that's less than 3 stars.

So if they don't face adversity when deliverying your package it's just not good enough? That's crazy.

Maybe give them a break, they're working hard.