Not only that, it's actually very hard to steal signs from second. Catchers change their indicators throughout the game, they don't just hold down a 1 and point to the outer corner lol. Runners will signal where the catcher is setting up on the plate all the time (which is why some catchers including Martin will often jump from one side to the other as a decoy) but relaying actual signs is not as easy as just being on second. Technology on the other hand you can monitor there signs throughout the game, have an accurate first hand of what's coming and with a little ingenuity find a way to relay that to the player.