international registered letter VS stamped letter

hi friends, i recently paid $20.50 for an international registered letter assuming it had tracking (as it was $20... like why else would the envelope be that expensive) i think i've made a mistake as it says on the auspost website that international registered can't be tracked, but everything i've read contradicts that by saying it gets scanned with the barcodes on it at faculties, etc. i'm just a bit confused as i don't actually know what the 20.50 that i paid has gone towards... i may as well have just sent stamped for $4 right?! please help