> I'm guessing your parents are still saving money overall, even accounting for the stuff thrown away.

I'm the same as OP, for the most part my parents would be buying the same stuff at the same store. They'll also be buying at the price on their weekly shopping day and if that's on a weekend when a lot of people shop then stores aren't discounting, whereas I can take advantage of daily specials or late night discounts.

> Two, the "keeping fridge stocked" model affords going to a cheaper store less frequently, and buy in bulk, saving considerable amount of money on a monthly basis.

You can do both, most thrown away food is of the more perishable varieties, so you can buy that on an as needed basis and buy stuff like tinned food in bulk.

Even the perishables can be bought somewhat in bulk. My wife ends up chucking an appreciable amount of perishables so I have thought about the economics--and her approach is generally the right one. Much of what gets chucked came from a store with good produce sales on Wednesday only. If she ends up chucking 20% of it but paid only 30% of what it would be at the store closer to home she's still way ahead.

>I'm guessing your parents are still saving money overall, even accounting for the stuff thrown away.

Probably. They make use of a farmers market heavily too & are probably more eco friendly on amount of packaging. So not really criticizing just find it crazy opening the fridge when I visit (once a year :( ) and am just stunned by how much food they keep for 2 people. At one point they had 2 full sized fridges.

Isn't this basically batch processing vs streaming?

This is the case where batching is significantly better than streaming, both in term of time and costs.