The concept of American exceptionalism does not include spelling things correctly. The main list of AOS spells it correctly. Pink-legged Goose was added to the AOU check-list in 1910 from accidental records from Greenland. I never knew the AOS had a US check-list. Why? Pyle 2018 is here:
https://www.birdpop.org/docs/pubs/Pyle_et_al_2018_29th_Report_of_the_ABA_Checklist_Committee.pdf .
The Washington State bird record committee rejected Pink-footed.
REPORTS NOT ACCEPTED BY THE COMMITTEE - IDENTIFICATION
CERTAIN, ORIGIN UNKNOWN
Pink-footed Goose (Anser brachyrhynchus). Two Pink-footed Geese
were found with Canada Geese (Branta canadensis) and Greater Whitefronted Geese (Anseralbifrons) in Hoquiam, Grays Harbor County, from 5
November 2003 to 10 January 2004, when one bird disappeared (P.
Sullivan; photo: R. Sullivan). The second bird was last seen there on 11
January 2004. A Pink-footed Goose, presumably one of the Hoquiam birds,
was then found about 30 km away in Elma, Grays Harbor County, on 21
February 2005, where it remained until 10 April 2005. The Pink-footed Goose was critically endangered, with Svalbard populations plummeting to less than 5000 in the 1950s and Greenland/Iceland
populations reaching a nadir of 20,000-30,000 in the 1930s; by the mid1990s, the Svalbard population exceeded 38,000 and the GreenlandlIceland population had reached about 250,000 (Boyd 2005). This increase
was paralleled by an increase in reports from North America (American
Birding Association 2002), and though there are no North American records
west of Pennsylvania (American Birding Association 2002), Washington
lies directly on a 1800 misorientation path for this species (i.e., a Greenland
or Iceland bred Pink-footed Goose oriented in the exact opposite direction
of its usual fall migratory path would eventually encounter Washington).
This species is rare but not unheard of in captivity (G. Toffic, in litt).
Consequently, the possibility the birds were escapees, coupled with the
lack of records west of Pennsylvania for this species or Greenland Greater
White-fronted Goose (A.a. flavirostris) led the Committee to reject this
record based on questions of origin.
The British Columbia committee ruled the same as Washington State, identification
of species is correct, but the origin as uncertain.
http://ibis.geog.ubc.ca/biodiversity/efauna/documents/PFGO-article-RT-DC.pdf .
The Colorado goose is from 2019 and I cannot find if the Colorado committee has acted.