“Essentially infinite” is a bit of a stretch. The minimum warranty period is 12 months but it is true that there’s no defined maximum period. The reasonably expected lifespan of a consumer good generally increases with its value. Manufacturers and retailers are free to offer further warranties in addition to the guaranteed warranty period under the consumer law but this does not reduce or replace your rights under the law.

I will add that change of mind refunds are not covered by Australian consumer law and it is uncommon for retailers to accept them compared to the US. You can usually exchange something for another item of equivalent value or store credit, but you usually can’t buy a phone to try out and return it after 30 days for example.