Why are face cards and tens worth zero in baccarat?

In baccarat, face cards and 10s are assigned a value of zero as a fundamental rule of the game's scoring system, rather than for a specific historical or mechanical reason beyond defining the game's unique arithmetic.1

The objective in baccarat is to achieve a hand total as close to nine as possible. To calculate this, the values of the cards are added together, but only the last digit of the total is considered significant. By assigning a value of zero to face cards and 10s, the game ensures that these cards do not increase the numerical count of a hand, which forces players to rely on the remaining cards to reach the target of nine. This scoring mechanic is what distinguishes baccarat from other games like blackjack, where cards carry different point values.1