It's rice. It's not like they're wasting anything significant, like the meat of an animal that gave its life. But still, the restaurant should have charged them for it at least, like every other all you can eat sushi place would have.
The exchange rate is usually better for grains than for e.g. chicken or even beef[0], though.
[0] https://animalvisuals.org/projects/1mc/ Note that I'm a little skeptical of the numbers here, particularly those for grass-fed beef. Not that it matters for the purpose of claiming rice has a cost in lives.
So any kind of waste that we can put a dollar value on, also has a value in human lives.
Make of that what you will.
> 33 field mice were fitted with radio collars and tracked before and after harvest. The researchers found that only 3 percent of them were actually killed by the combine harvester (amounting to one mouse). An additional 52 percent of them (17 mice) were killed following harvest by predators such as owls and weasels, possibly due to their loss of the crop cover. It is unknown how many of these mice would have been eaten by owls or weasels anyway.
That last sentence is key: without a control you can't draw much from this experiment.
Additionally, while they say "animals" many times they're not clear on which ones they're including. The decision on whether to consider insects would be especially important.
How is that not a completely useless waste of energy, time, money and resources?
I'm in the "every life is sacred" camp, but...even if you do kill one animal and leave it to rot, it's not a total waste, just a "cruel" one.
Other things feed off of the carcasses of animals the same as you or I do. We just consider all other organisms beneath us, so if we kill and discard something, we write it off as a total waste. Birds, dogs, rodents and microorganisms disagree.
Carbohydrates are much cheaper than proteins and fat.
Proteins and fat of vegetable origin are cheaper than those of animal origin, but they come accompanied by excessive amounts of carbohydrates.
The most efficient way of getting food for human consumption for now is to dump as waste most of the carbohydrates from vegetables and retain only the valuable proteins and fat (this can be done at home for instance by making bread but washing the dough before baking in order to remove most of the starch, producing thus a protein-enriched bread, or by removing completely the starch by extra washing of the dough, converting in into gluten a.k.a. seitan).
The high proportion of carbohydrates from vegetable food can be used completely only by those who do hard physical work, but not by those who have a sedentary lifestyle, who must necessarily dump the carbohydrates as waste, either directly or indirectly (by buying food where the carbohydrates have already been wasted in various ways, including as energy sources for animals that have been raised for becoming food).
In the future it might be possible to develop better ways to use the carbohydrates that must be wasted now, by converting them with high efficiency into proteins or fat, by using bacterial or fungal cultures.
Are you arguing that everyone should be vegetarian? That's a topic I was not even remotely touching on.
For now, there exists no way of producing enough proteins and fats without also producing an excessive amount of carbohydrates, which must be wasted in some way or another.
One way of using the excess amount of carbohydrates from vegetable food is by feeding animals or mushrooms, to obtain food with a more favorable proportion of proteins or fat (and this is a form of food wasting, as less food is obtained as output than it is provided as input), but another way is just dumping the excess carbohydrates (i.e. starch or sugars), after using food processing methods that separate the protein-rich or fat-rich parts.
When humans eat the excess amount of carbohydrates instead of dumping them as waste, the result is obesity, which is a worse choice than wasting the undesirable food.
Food in general is a significant part of our ecological footprint. Rice has a relatively high impact for a crop. Of course it's still in a different ballpark than beef.
I'm guessing it's very, very small.
But, when it comes to the real deal. Sushi from a tier one or two Japanese sushi chef then the rice is actually the most important factor in making good sushi.
Discarding the rice would be seen as comparatively barbarian as dunking a freshly made piece of sushi by a good chef into this mixture of soya sauce and ersatz "wasabi".
I've never had either.