Narrating the Star Wars scroll is one thing, they would have had to refilm it in dozens of languages otherwise.
The Italian THX narration is just the dumb it down sort of over explaining things that happened with the original release of Blade Runner. Lucas would never have signed off on it, nor reframe the entire film as a flashback.
Unless somebody has Robert Duvall's cell phone number, (provided WB didn't use a sound-alike) we may never know for sure. But we can make some educated guesses. Moving the big chase scene to the beginning smells of studio thinking.