i think the scores are basically a measure of visual match and possibly some other factors like presence of observations of a taxon nearby. i think that’s why iNat staff don’t want people thinking of it as a probability or confidence.
so, for example, suppose you have 3 brothers A, B, and C. A & B are identical twins. suppose you take a picture of A and run it through a computer vision algorithm similar to iNaturalist’s. i would expect that CV to return scores that might be like this:
F: 0.97 – the family of A, B, & C
A: 0.95
B: 0.93
C: 0.65
D: 0.35 – D is the boy who lives next door.
so obviously, the CV couldn’t be both 95% sure the photo was of A and also 93% sure that it was of B, nor would it make sense to assign 95% probability of A and at the same time assign 93% probability of B, but by seeing the relative scores, you could see that the CV was saying that A and B were way better potential matches than C or D.