Update: thank you everyone! user @Today has provided a great link of a discussion that suggests the correct answer is where being an abbreviation of, whereas as a replacement of since, hypothesized in these comments.
As I love archaic definitions, I’m more convinced to now that this is the answer!
Especially since the question originates from one weirdo using “where” instead of since.
https://english.stackexchange.com/questions/338694/is-it-ever-appropriate-to-use-where-instead-of-because-or-since
Like “Where we knew he was heading to Chicago tomorrow, we got on the first plane heading east to intercept.”
“Where we knew where the safe was, we began to cut through the wall in the corner behind her desk.”
Thanks
That’s the interesting thing, its usage is very specific and not like the instruction examples you provided
It’s used consistently throughout a book in exactly your beer scenario, or let me grab the other almost exact examples from another comment:
“Where I was on the bed, I leaned around the corner to look into the hallway”.
“‘Where most of the animals are scared, I can’t see the point of scaring them further.’”
“Where they can pick locks, they might already know what’s in the safe!”
So yeah, wouldn’t work in standard English, but they consistently use where instead of sense in these kinds of sentences.