IMO, it isn't "obvious" because it all makes sense that it could have been DR until you try to imagine what DR would have done AFTER he had Jacob (if he had indeed taken him.)
1. Knock Jacob over the head and stick him in his basement or an outbuilding and hope the cops wouldn't come and search?
2. Run holding Jacob and hide him somewhere on his land?
It just doesn't seem possible to me. He had no way of knowing LE would skip so many vital steps because they were concentrating on Jacob having been taken in a car. (Even though he was the one who said there was a car.) I feel, being intelligent, he would have assumed cops would search his home and his land, since it happened at the end of his driveway.
I do think there were some stories made up (or exaggerated) by DR about earlier cars flying through his yard, because tracks did not prove that. I agree that a car that drove fast through his yard in the afternoon would have had nothing to do with an abduction later that night anyway.
I think that rather than having abducted Jacob himself, he has an inkling who did take him, and thus the changing stories, the vagueness about cars and "what I saw" as he tries (IMO) to prevent this other person from being looked at.
Early reports from detectives, FBI and media on the case did NOT mention anything but DR having seen one small dark car in his driveway. These other cars were never mentioned by DR until after 2003/04 when Kevin came forward with his story of having been in DR's driveway. (You can search all through any reports that have been made public and news articles or interviews from 1989 to 2003 for proof of this - the extra cars were never mentioned until after Kevin's story was made public.)
I do NOT feel Jacob's and Josh's (or the Reker girls) cases are connected. My own opinion on Josh G. is that he was taken by someone from the abbey. As Trino stated, the bloodhounds tracked Josh's scent to the abbey, and then LE was not allowed inside. The Reker girls have been strongly tied to Eckroth (in our who's who) and someone who knew Mary's bf. I still think there is a possibility that Jacob's and Jared's cases could be connected somehow.