It can be waxed paper, accomplishes the same purpose.
I have an issue with disposable plastic food containers. So obnoxious. Some processed food has more packaging than actual food. Like plastic sushi boxes with the stupid plastic grass between the pieces.
A recent plastic bottle and aluminium can tax was introduced in my country, thanx to the EU, which has led me to change my behaviour from avoid to avoid at all costs.
Scientists found microplastics in clogged arteries. Soon we won't have just high cholesterol, but also "high plastics" in our bloodstream, as if plthalates that were linked to high cholesterol were not enough.
Most sugar I see sold (and probably flour too) is sold in plastic bags, not paper. You can probably find the really huge sizes in paper, but the smaller sizes that most people want (because of convenience, they don't want to buy a decade's worth of sugar at one time) are usually in plastic.
But these numerous little exceptions don't invalidate OP's observation, wherein: Our needs have broadly changed, and thus so has our packaging.