Because units less than a litre are so common. 2ml of syrup, 4dl of flour, 12cl of wine, 0.5l of beer, etc. But things you measure by mass rarely go below 1 gram (in day-to-day life at home). Candy bar is 50g, a packet of cheese is 200g, a chunk of meat is a kilogram. Besides, most people just call it “a kilo” so the common units in the spoken language are “a kilo” when talking about mass and “a litre” when talking about volume
You don’t seem to have understood the question.
1 kilogram is 1000 grams. Kilo isnused in place of the 1000.
1 litre of water weighs 1000 grams. Why couldn’t it be 1 litre of water is 1 gram?
Because units less than a litre are so common. 2ml of syrup, 4dl of flour, 12cl of wine, 0.5l of beer, etc. But things you measure by mass rarely go below 1 gram (in day-to-day life at home). Candy bar is 50g, a packet of cheese is 200g, a chunk of meat is a kilogram. Besides, most people just call it “a kilo” so the common units in the spoken language are “a kilo” when talking about mass and “a litre” when talking about volume