I believe there are errors built into the system and putting is affected in a couple of ways. I am a raw beginner, but I have had puts for birdie which had no elevation changes at all, and I hit the put perfectly and my distance was perfect, but I missed the put. Why? Well, my theory is that all clubs are imperfect, and that's what they mean by precision. If a putter is less than five dots of precision -which I believe all of them are, then there is a margin for error.
One question is, is the error random or does the game choose the times to add the error? I notice the error is not added nearly as much on puts for par as they are for birdie. I swear I have had totally flat greens miss when they said my stroke was "excellent" and the distance was perfect since my ball stopped just past the cup.
Probably, this is a good thing and adds to the challenge. Overcoming the error is possible with puts which would go by the hole at least one foot. That seems to be one secret to good putting. Puts which are exactly the correct distance will often curve off one way or the other.