It is without a doubt a Lesser Goldfinch. The very pointed finch bill is quite unlike the more swollen, paler, larger bill of WETA. I guess I could understand some confusion over a single photo by some people, but these birds are nothing alike in field observation, as far as size, behavior, calls, etc. Also look for the whitish flash at the base of the primaries, visible from above and below, on Lesser Goldfinch, diminished in fem/imm compared to males, but still apparent when they fly. It's always good to accompany a photo with notes taken in the field on the bird's behavior, vocalizations, size compared to any nearby birds (if there are any), and any other impressions you get in the field (aka jizz, or giss (general impression of size and shape)). LEGO has pretty distinctive calls and is fairly vocal, especially when taking flight. Most American Goldfinches, and male Lesser, typically show white patches on the underside of the tail, like in the view here, but female Lesser lacks the pale areas and show all-dark tail like this bird. (western tanager also has all-dark tail but this is not any tanager so it's irrelevant). Also, I do not see any tooth on the upper mandible on this bird, but I do see what looks like a bit of food stuck to the bill there, which would disappear as soon as this finch wipes her bill on a nearby twig.
EBird/Macaulay Library online has countless great photos of all these ages/sexes of Lesser Goldfinch, and Western Tanager, online, to compare with Bill's photos.
Good birding,
Derek Hill