> I find people who argue scarcity more often than not don't have actual numbers to back it up. Amongst human beings biggest necessities, what are actually scarce?
Scarcity in the economic sense just means there are material limits to the things people want. It's not a synonym for "rarity."
> Food? Not at all, tons and tons are thrown out daily.
The places that are throwing out food also have charities and food banks so that few people actually starve to death. People who starve to death are in parts of the world with poorly functioning distribution systems. The people in those parts of the world who have food don't throw it out, they lock it up so they can give it to their friends.
> Housing? Well there's enough of that for everyone we just don't know how, and don't want to, distribute it.
This is a good point and there are homeless people in cities with vacant housing.
> Clothing? Even though people burn through clothing almost as quickly as food, it is produced in surplus so much that we invented fashion.
Crucially, there are very few naked people but the things people want to wear are still of limited supply.
> Classical economics has no explanation for this modern surplus of production.
Its literally called "capitalism"; People with means of production make profit by producing commodities and this incentivizes other people to invest their surplus in additional capital and compete to produce more commodities. This expansion of production drives the marginal rate of profit down which causes people to invest in producing other things; the capital and products are thereby multiplied over and over and the result is a system that makes these basic things extremely plentiful and low cost.
> What necessity exactly is scarce in 2020?
Human labor, time, space, raw materials, and products that are the output of specific processes that cannot be commodified in this way (art, haute couture, and antiques are examples)