Why do League of Legends markets Map QuadraKill and Map PentaKill only have a 1-way selection (”Yes”)?

In practice, the Quadra kill and Penta kill markets are only offered when the “Yes” outcome is viable, while the odds on “No” are so low that it doesn’t make sense to offer it. Therefore, these markets should be 2-way, but because of their internal dynamics in practice they are only 1-way.