Like for Pepsi it will show $1.67/per litre, for instance.
Then you can easily shop all the 24 or 30 multipacks.
Also, like other countries the actual weight inside the same packaging are shrinking. Chocolate Bars are a good example.
They've tried pushing the smaller than 350ml can size, but it hasnt stuck. In the UK they have a 330ml can size.
Source: I work in Marketing and currently am working for retail FMCG and F&B clients, so research things on shelves more than your average human :-)
Well there are the new taller cans that look 'bigger'. even though it probably costs more to make those in terms of aluminium ammounts.
I will readily say that the above is a luxury that not everybody has, but then buying the best per oz price is a luxury not everybody has either. Certainly there are oddball cases like you pointed out, but typically the larger items have a better per oz pricing and not everybody can afford the higher upfront price even if the per item price is less.
The person that buys the overpriced "value" pack is basically giving money to PepsiCo or whatever, but in effect that subsidizes the conscientious consumer.