Aves have 6.36:1 observer to identifier ratio
Actinopterygii 5.46:1
Insecta 9:43:1
Magnoliopsida 11.17:1
I think that’s illustrative of why some groups are able to keep up with new observations better. Also, I suspect the CV is better at identifying birds, because there are
a) fewer species
b) plumage is often very obvious, and
c) common, easy birds come up a lot (15 species have 100,000 records or more).
Additionally, I dare say most users know birds better than plants, so the number of identifications need to clear the pile is probably lower than these other groups (just one click for RG and move on).