Why are misplaced modifiers such a common grammatical error? Plus, what's the difference between a misplaced modifier and a dangling modifier?

So when you say, “I saw you working,” you get a grammatical sentence with a verb (saw), followed by its object (you), followed by a modifier of that object (working).

Terence Parsons, Some Problems concerning the Logic of Grammatical Modifiers, Synthese, Vol. 21, No. 3/4, Semantics of Natural Language, I (Oct., 1970), pp. 320-334 ...

Yet it’s clearly correct because the structure, with “Jen” as a noun and “walking” as a modifier of the noun, is both grammatical and standard.

Reading your writing in a new form — for example, on paper instead of on a screen; in a different font; or out loud — can be helpful in finding typos or grammatical errors.

Broad match modifiers help advertisers control the intent of users seeing ads, but Bing says advertisers may have been missing out because of grammatical errors in queries.