To add more into the mix, I would say "Scheduled in" (verb/preposition) can be used for creating a schedule — "The timetable for the June exams will be scheduled in the last week of May". People also use "scheduled-in" in place of just "scheduled" to mean the same thing — "I have your appointment scheduled-in for next Monday". See also this question. So would normally know by context which ...

prepositions - Scheduled FOR or IN the next days - English Language ...

The author had a choice between "scheduled for a confirmation" and "scheduled to appear at a confirmation" and between the two choices, produced a bastard of the pair.

word choice - "Scheduled to" vs. "scheduled for" - English Language ...

Why is a just a rather odd wh -word. Its distribution is very limited -- it can only have the word reason as its antecedent, and since it's never the subject it's always deletable. Consequently it behaves strangely, as you and others point out.

The grass is wet because it rained last night. This seems the simplest and most elegant expression of the meaning. I am always suspicious of "reason (s)" and "why" being next to each other. There can be reasons for things but there is usually a better way of expressing "reasons why".