If it's like the UK, there is so much "shrinkflation" (reduction in product size [and cheapening of ingredients]) that prices comparison is going to need per gram pricing. Identical looking packs now have extra air gaps: inflated chocolate bar wrappers, ice-cream cones with a 1cm gap below the lid, butter cartons have a recessed base, packages that formerly had straight sides now taper, etc. ... lots of these "tricks" already existed but they're being used more and more.
All the supermarkets have full inventory databases, they could send you an updated price list of every product every five minutes at basically no cost. This smacks of a legislature don't/won't seek advice from experts. It's a start I suppose.
> that prices comparison is going to need per gram pricing
Not entirely sure what you mean here, but we do have per gram pricing requirements (expressed in £/KG).
EDIT: oh you mean that shrinkflation is so bad that £/gram will make more sense. Hah yeah
The trouble is that grocers have figured out that if you fool the population in to using a 'loyalty' card, you can make everything a 'promotional price' and avoid the per-unit labelling requirements. They just show the £/KG price of the higher price. So now consumers can't easily compare. [0]
All of this can be avoided by just shopping at e.g. Aldi and Lidl, but I would not be surprised if even they succumb to the temptation of a loyalty-card-only pricing very soon. (Though they too have partaken in shrinkflation)
> The trouble is that grocers have figured out that if you fool the population in to using a 'loyalty' card, you can make everything a 'promotional price' and avoid the per-unit labelling requirements. They just show the £/KG price of the higher price. So now consumers can't easily compare. [0]
That is illegal in the Netherlands: You must advertise with the normal price. You can display the "promotional price" but it cannot be your main price. What they usually try is adding a "25% off with card" option next to it or with a second price card. You however CAN NOT be denied the discount in any way even if you do not subscribe! This is less easy to do online but offline the shop will have to give you the discount.
There is one exception: b2b.
I complained about this when a liquor chain (gall & gall) started using their "card holder" prices as the regular prices on the cards and displayed the regular ones almost invisible (black text on blue background ...). They refused to provide the discount price to non card holders. Complained to the regulatory institution and got back to me that they were already looking into it. No fine was charged but the practice stopped after a few weeks.
edit: on a more HN note; if you use the apps for the discount of the stores they usually have an agree notice which includes, among other things, you can be tracked in the shop with the app. Never be logged in to those while in the shop (or ever).
It seems like we have all of the tools necessary to take a picture of a segment of store shelf and have the price data extracted from the photo, associated with the item itself, cross referenced, etc, and then show you an overlay with the best deals highlighted.
I shop there 2-3 times a week and wouldn't really say "rapidly". Or if they do, the swings aren't big enough for me to notice.
Though looking at their site, I think they are partaking in the old "raise prices for a short period then show them as a 'sale' price" nonsense. But it only seems to be £0.10-£0.30 and the higher prices aren't even that offensive (yes I have a soft spot for Aldi :D).
I would like to see companies forced to show the period that the higher price was charged for.
In the UK the supermarkets (I assume they have to by law) quote the weight of contents of a single unit of product (which is supposed to be total weight - packaging weight), so you could analyse this quite rapidly.
They don't, some items are per unit, which is a way that avoid comparisons for fruit. In [my local] Tesco they even took away the manual scales now, making comparison across 5 different types of apples, say, much harder. Good mental-arithmetic practice.
All the supermarkets have full inventory databases, they could send you an updated price list of every product every five minutes at basically no cost. This smacks of a legislature don't/won't seek advice from experts. It's a start I suppose.