The drawback of virtual school is lack of human contact, as opposed to a noted merit of traditional education, providing students with ongoing daily interaction with teachers.
The relationship of the appositives looks like this:
lack of human contact = -1*(a noted merit of traditional education = providing students...)
-1 = as opposed to
The phrase in brackets defines the opposite of the phrase on the left hand side in the equation, right? In other words, the definer defines the opposite of the defined on the left hand side. This is a minus-apposition, a term I have just invented. What do you think, Frank?
I have left unresolved so far the function of "as opposed to". Sto eto? Was ist das? What is that? Que es eso? Vad är det?
IMO it is this: explicit indicator of minus-apposition.
"We have normal indicators of apposition, e.g., for example, to wit, that is, namely, in other words, etc.
"(A)s opposed to" is a not normal indicator. It indicates the "minus one times" idea of the preceding appositive.
The participle clause is in normal apposition to "a noted merit of trad. edu."
What we have in this sentence is "more than two units in apposition".