The monopoly has been making close to a billion per year in profits and not one cent goes into Australian taxpayer or Government coffers.
According to their 2019 financial report they made $286m before tax. Any Australian taxpayer who directly owns shares or has them in their super fund is making money (39 of those not one cents per share actually) out of Sydney Airport. They have losses to offset against their profit, so no tax ($71m according to the same report) paid (just like Qantas did for 10 years). Pretty much par for the course for an any savvy business accounting, or the average taxpayer if he's smart.