No. The majority of vegetables I buy (in Canada but it's the same in the US as far as I've seen) are not pre-packaged. Self checkouts have a scale built into them that you weigh your own produce and punch in the code to say what kind of food it is. It's trivial to cheat if you want, but most people are honest. This is also true in hardware store self checkouts where you buy loose items and the store relies on you being honest about punching in the correct code when you check out.

Not exactly. Typically there will be a sign that lets you know how much the produce is per imperial pound. There are analog scales there that you can use to weigh your produce to give you an idea of how much it will be, but the real digital scales are at checkout. At self-checkout you put the produce onto a scale and then click on the picture of the produce your are purchasing so the computer can correlate the weight with the item. There isn't anything stopping you from clicking the picture of a cheaper produce item other than the honesty system.

... and the staff member hovering around the self check out area.

Not around where I live. They hang out about 15 feet away.

Who is definitely going to notice the that you rung up something expensive as something cheap...

> already weighed and tagged portions

generally no. They do sell stuff like that as well, but most is out in the open and you bag yourself. And then punch in the item codes or look them up at the self checkout. There's no real check, although sometimes they catch people cheating by reviewing video.

Here in the UK, like the US, the self-checkout machines have built-in scales that weigh your produce and calculate the price automatically.

There's no extra tags involved, you just have to select what the produce is if it doesn't have a barcode.

There is indeed an opportunity to "cheat" by weighing something expensive but telling the machine it's something cheap like onions or potatoes.

But the machines can be monitored remotely from a security station, so there is a small chance you'd get caught. That keeps most people pretty honest.

I'm sure a few cheats do slip though, but the losses from this sort of thing are presumably much less than the savings from employing less checkout staff!

Here in Toronto, we have both. In fact, one location of a grocery chain might allow you to tag and weigh your own items, whereas another location of the same grocery chain might require an attendant (usually right next to the automated machines) to verify it.

I've seen one location go from requiring an assistant to allowing full self-serve.

Not sure about the U.S. but I have the impression that there must be places which are similar in the U.S.