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Comment by remarkEon | Hacker News Reader

Airports make a lot of sense to me. Movie theatres kind of do. Supermarkets don’t. If I squint hard enough I can see it working (I’ve been to the Go store a couple times and it is indeed a great if weird experience), but food like vegetables seems harder to do this with than prepackaged sandwiches and sodas. How do you handle things that are priced by weight? For example potatoes, or steak. Make the customer print a label with a QR code the cameras can read? That sounds like a terrible experience, and the “solve” is more packaging and trash - something Amazon already causes a lot of.

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> How do you handle things that are priced by weight?

I assume they'll handle it the same way Amazon Prime Now seems to handle delivery from Whole Foods: it's a platform where weight doesn't actually matter.

I get insanely variable results when I have Whole Foods items delivered via Amazon Prime. 2 lbs of chicken breast might be as little as 1.2 lbs, or as much as 2.5 lbs. In either case, it's priced as 2.0 lbs. If you're savvy enough to weigh it and realize you've been stiffed, Amazon refunds the entire item, so it's a win for the consumer...I guess?

In general I find that my weight-based fruit/vegetable/meat/bulk bin item purchases via Prime Now slightly exceed whatever I actually requested and paid for, and Amazon never charges for delivering more than you initially requested. But maybe 1/8th of weight-based items will be drastically under-weight. I have a kitchen scale handy, so I always catch this and report it. Amazon has never failed to refund the full cost of the item, but I do wonder how many other consumers are never noticing that they've been scammed when Prime Now fails to deliver the weight that was paid for.

Here in Germany, it's common to weigh goods that are priced by weight and then have a sticker printed out to stick on them for the cashier. I don't see printing a QR code or whatever weird mechanism Amazon uses to price items being much more complex

Interesting. I am skeptical that US consumers would have the discipline to do this. Maybe another way to solve this problem would be adding a weigh station next to each SKU (or group of SKUs), and then the station logs the weight in the app as the customer puts the item in their bag?

That’s also common, in the self-checkout machines. Instead of scanning the barcode you just drop the item on the surface and select it on the screen.

True, I didn’t consider that. I suppose it’s not that expensive to put scales everywhere.

Depends on the state in the US. Almost every state has relatively strict requirements regarding which models of scales may be used for trade (pricing), and some impose taxes and other fees to keep them in operation. Most scales on grocer floors that are accessible to customers (if you can even find them these days) are clearly marked as "not legal for trade" or have a similar disclaimer -- precisely because it would be too expensive to keep carefully calibrated trade-legal scales exposed to the general public.

I had no idea this was a thing, but I’m glad that it is actually a thing.

in nj, scales are inspected by the local Office of Weights and Measures. mis-calibrated scales can result in a fine for the grocer.

Meijer (US megastore retailer that competes against Walmart in the American midwest, though generally has slightly higher prices and higher quality items) has introduced this recently with app-based self-checkout, and it's picking up adoption at a fairly quick pace.

Another huge regional grocer, HEB, does this in Texas with their largest and most upscale stores, and it's been a norm for nearly a decade.

That would still require you to scan something. You don't scan anything here - you just take what you want off the shelf and leave.

What if the customer took the vegetable and put it in a bag which sits on a scale right in front of the shelf. Then they take the bag and go.

Alternatively, the entire shelf is a scale, but the shelves are smaller so that only one person can pick vegetables at a time.

Forcing the customer to drop the item(s) on a scale seems most reasonable, but requires relatively strong controls to ensure the customer isn't pulling shenanigans like placing item A and item B into a bag, then co-mingling them when weighing them later.

As long as you don’t have more than one person picking up produce from a bin at the same time you can just measure the change in weight from the bin it’s taken out of. That has to be super cheap technology at this point.

Seems complicated. Even if you're resetting tare on the bin regularly, fruits and vegetables can have significant changes in weight due to dehydration, and most markets are doing things like misting chilled produce with water, which will introduce constant and somewhat unpredictable changes in bin weight.

The tare would be reset each time a customer picks something up. The total bin weight doesn’t matter, just the delta between before and after the computer vision system identifies that a customer removed some of the bin’s contents.

>The tare would be reset each time a customer picks something up.

This would run afoul of commerce laws in pretty much every US state. Tare must be set from zero, not relative to whatever happens to be on the scale, and certainly not on the fly.

For produce, you could turn the shelf into a scale. It reads X before the camera detects the customer picking up the item to put in their cart, and it reads Y after. Therefore the potatoes they picked up weigh X-Y.

Another approach would be to have a scale and require them to stick their potatoes on it, but not require the other, tedious steps like entering a PLU code or printing a sticker. If you can track them picking up items off a shelf and putting them in their cart, presumably you can also track an additional intermediate step where they put it on a scale. (And connect that scale to the network, take a reading when you see them stick potatoes on it, and correlate that.)

Of course you can always just sell by unit and not in bulk. Sell 1 pound, 2 pound, and 5 pound, and 10 pound bags of potatoes instead. Maybe even 0.5 pound if someone wants a small quantity. Or for things whose size doesn't vary much (like apples), just sell by number of apples.

For steak, the packages are normally already weighed and labeled, so the problem might be easier if you can just scan a label that's already printed.

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