Earlier quoted context omitted.
This comment has no place at the top of the page. > the problem with RFCs is the archaic writing style I'll admit, reading standards is more difficult than reading regular prose, it is nearly impossible to use language precisely without getting too verbose. Languages, and English especially, are full of little ambiguities; even simple words like "or" have more than one meaning! This doesn't quite cut it when it comes…
Let's take a look. Oxford says "should" implies "used to indicate obligation, duty, or correctness"[0]. That sure does not sound like "aren't required to" to me. Sure enough, if you look into "must" [1] you see that it is defined as "be obliged to; should". Maybe you shouldn't be chiding people implying how simple English is when you're not so solid on it yourself, especially when you've given a whole treatise in you…
In fact, looking at it, you dropped half of the definition you pulled for "should" ("typically when criticizing someone's actions") and I will claim are mischaracterizing what an "obligation" is (just because I am obligated to do something, doesn't mean it is a necessity for me to do it).
Putting this into practice, if you tell someone that they /should/ stop at the kiosk before parking in the lot, normal speakers of English will treat that drastically differently than if you instead say that they /must/ stop at the kiosk before parking in the lot; the former feels subjective while the latter feels objective.
For a rather clear example of this: "you /must/ open the drawer before you [can] take things out of it" would go unquestioned, while "you /should/ open the drawer before you take things out of it" will cause many people to wonder what the alternative to opening the drawer could be.
(edit: I see that chc made a similar complaint about your comment to me 10 minutes earlier, but I didn't see that comment as I was working on mine; I think mine has some value still with the examples, and a slightly different focus, so I will leave it in the thread as a reply.)