For what it’s worth, when I first saw ROTJ in '83 I assumed the ghostly Shaw was appearing in Tatooine garb by way of symbolising a return to some sort of pre-war innocence. In the original canon (ie the novelisation of SW) Anakin had been a farmer like Owen, and was obviously recruited by Obi Wan for some kind of ‘crusade’. So I thought he was merely appearing in his old farmer duds for Luke’s benefit - kind of a “here’s how I would’ve looked if I hadn’t become a war criminal at the right hand of Hitler” type thing. It never occurred to me that Lucas intended that outfit to represent official Jedi threads (which is absurd IMO).