

I think that goes to my point about simple comparisons being difficult. Norway has a high GDP relative to its size, so 4% might be more than enough for their situation. You also have to account for things like the labor cost of teachers, which varies by country.
It depends on your plumbing. If your sink’s waste pipe is large enough, and has enough slope, and you put enough water down the drain to wash all the solids through the pipe, then you can certainly put food down the sink drain.
In my house the kitchen sink’s waste pipe is smaller than what the toilets use. And it makes a long, minimally-sloped run to the main sewer connection. That pipe will clog in a hurry if I put food down the kitchen sink drain.