Do your provide taxi travel through ride-sourcing? If so, you must register for GST regardless of turnover.
See following a recent ATO post on this topic: Providing taxi travel services through ride-sourcing and your tax obligations. The views in this product relate to the meaning of the word ‘taxi’ as it appears in the GST law. For GST purposes, the word taxi takes on its broad ordinary meaning of a car (vehicle) [...]