Why do one-wall and three-wall handball courts allow more spectators to watch?

One-wall and three-wall handball courts allow more spectators to watch because they are not fully enclosed, unlike the standard four-wall court.123

By having open sides or an open back, these court designs remove the physical barriers that typically restrict viewing in an enclosed four-wall environment. Additionally, these open-court configurations are generally less expensive to construct than fully enclosed facilities. While the development of glass walls has since allowed for increased spectator capacity in four-wall matches, the open nature of one-wall and three-wall courts remains a primary factor in their accessibility for audiences.231