Note that the machines have many tolerances that can be set to trade-off theft vs. annoyance of the customer. (E.g. the product weight when placed in the bagging area.) The machines can we way less annoying when they are set to be more trusting.
I also generally found them to work better in Australia than in the US, though the technology seems to be the same. I guess it's because of these tolerances being set differently, but that's just speculation.
You could be correct, just recently the Australian supermarkets announced a crackdown on self-checkout theft (mentioned in the podcast) which would seem unlikely if tolerances weren't currently lenient. In the last week the Coles supermarket I went to had rolled out entirely new software / UI on the machines, and for the first time in ages there were long self checkout queues and people seemed to be taking longer.
I also generally found them to work better in Australia than in the US, though the technology seems to be the same. I guess it's because of these tolerances being set differently, but that's just speculation.