Recently, a former Rockstar Games employee (Obbe Vermeij) who worked on GTA 3 shared why Claude (the main character) is always silent during the gameplay (in later games of the series, characters do speak).
According to him, part of the reason was that the recording studio was too busy at the time. However, there's another version presented by Rockstar Games. They wanted Claude's constant silence to make it easier for players to associate themselves with the main character.
GTA 3 was released in 2001. At that time, voice acting for main characters wasn't as common as it is in modern games, so Claude's silence likely didn't draw much attention. By the way, Grand Theft Auto: The Trilogy — The Definitive Edition, which includes remasters of GTA 3, Vice City, and San Andreas, was recently released on Android and iOS mobile platforms. The trilogy had earlier been released on PC, PS4, PS5, Xbox One, Xbox Series X/S, and Nintendo Switch.