Just look at a "wing nut"- they're perfectly designed for parrot beaks to play with, and they're even named after parrots! A smart parrot may have even invented them! If you give a parrot a wing nut you can't expect him to ignore it- same with food dishes. Their favorite things go in them so of course they will be drawn to them!
I want to know why a parrot can't sit on a shoulder without wanting to bite an ear! It's like the ear is asking for it by dangling its floppy, fleshy self at beak level! Add a shiny sparking earring and it's over- Instant parrot toy!