Why do I get vegetables by the kilo?

I went to the Nachtmarkt, which has a wonderful selection of spices and a surprising variety of asian food (homemade tofu!). Most of the produce comes from Italy.

My inability to speak German resulted in the purchase of one kilogram of spinach, which is in fact heavier than one kilogram of anything else because it comes with odd stares on the metro. (Imagine getting onto a crowded subway with a Costco-sized bag of carrots. Or a sofa pillow full of green leaves).