Because you don't get to choose your vegetables; they choose you.
This is a carrot. Apparently, carrots don't all come in the comforting, non-trifurcated shape you are used to. And you know why you've never seen this carrot? Because the grocery store won't take it. The grocery store only wants pretty produce, the kind that shows very little signs of ever having touched the earth. The grocery store wants huge, cascading mountains of fire-engine tomatoes and glossy apples. Its intentions may once have been good--scary looking produce has a better chance of being diseased produce--but have become instead a marketing strategy designed to give you warm, fuzzy feelings about your purchasing options and make you want to use them.
Do I sound cynical? I will now admit that I marched down to Whole Foods today and bought several items from their displays (though, I must say, I was hunting for their reassuring signs, "I'm a Local!", indicating food that has come from nearby farms). Wandering the produce aisles in big, fancy grocery stores is, for me, like gliding dreamily through shoe stores for some women or scholars losing themselves amid towers of titles in bookstores. It's comforting. It's attractive. It makes me hungry.
But it's also a bit of an illusion. A disappointingly mediocre amount of those piles will actually be purchased, taken home, and eaten. It seems the only way to convince us that we want something is to show us more than we will ever need, and then throw half of it away.