At least in Australia Temu hits the sweet spot of offering almost-China prices with reasonably speedy delivery (under a week). If you buy the same crap on Amazon.au, you pay a 3-4x premium for local warehousing, and if you buy it off AliExpress, it often takes a month or longer to deliver.
That said, I presume the only way Temu can pull this off logistically is air freight, so I also have my doubts about his sustainable this is.