No this is different. At SIN most flights arrive and you are directly on the concourse mingling with departing pax - you then head to immigration, or get rescreened at gate of your onward flight. Some flights (a % of the ones from BKK, CGK, etc) get rescreened on arrival before you enter the concourse.

Screening for biosecurity at Australia, New Zealand, and some other countries, happens for ALL arriving international passengers just past immigration.

The distinction is the SIN checks are your carry-ons only, whereas for Australia/NZ/etc it is both carry-ons and checked luggage. I suppose at SIN your pockets are also checked if you trigger the WTMD but you could in theory smuggle stuff through in your pockets or elsewhere on your body.