One of the properties of governments is tending to take things seriously, whether or not this is a good thing is a discussion that someone else can have. Anyway, the US Federal web guidelines are the sort of thing that a serious organization can produce:
https://standards.usa.gov/getting-started/developers/
and so are the UK's:
https://www.gov.uk/service-manual/helping-people-to-use-your...
On the flip side, because Google penalizes sites for not looking pretty on mobile but not for inaccessibility, day to day we can tend to get caught up in its priorities rather than thinking about accessibility.
Good luck.