[qwertimus]

This is standard at self-service checkouts in Australia. Both Coles & Woolworths (the 2 main supermarkets) have this imployed. Unrelated to the topic, they also watch what you bag and will lock up and sound an alarm if it think you've added an item without paying. Absolutely atrocious. But back on-topic, these stores also have cameras in every single aisle, from ever perspective. They absolutely track people throughout each store.

[waste_monk]

I believe they also have cameras watching the scales / scanner platform. If you put e.g. an orange on it and then choose to manually input what type of item it is, orange is usually the first item on the list of suggested possibilities.

Do the same experiment with the orange in an opaque bag and it will still usually have it on the list (guessing by weight) but not always at the front of the list.

I would assume this will also trigger an alarm if you were to try tricking the system by obscuring the barcode on some steak and checking it out as apples by weight (but have not tested this hypothesis for obvious reasons).